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128
Chan et al.: Non-native shes of Hong Kong
The non-native freshwater shes of Hong Kong: diversity, distributions,
and origins
Jeffery C.F. Chan1,2*, Alphonse H.F. Tsang3, Sze-man Yau2, Tommy C.H. Hui4, Anthony Lau2, Heok
Hui Tan5, Bi Wei Low2, David Dudgeon1 & Jia Huan Liew1,2*
Abstract. Non-native shes are widespread in Hong Kong and many are likely to be established. Extensive eld
surveys, literature reviews, and citizen science data were used to determine the diversity, geographic distribution,
potential introduction sources, and known impacts of non-native freshwater shes in Hong Kong. In total, 95
species, including ve putative hybrids, were recorded. In comparison, there are 65 species of native freshwater
shes. The majority (62 species) of non-native shes belonged to ve families: Cichlidae (27 species), Cyprinidae
(15 species), Poeciliidae (eight species), Xenocyprididae (eight species), and Channidae (four species). Half of
all non-native species had at least one breeding population. Potential introduction sources were grouped broadly
into three categories: aquarium trade (associated with 62 species and two hybrids); aquaculture (20 species and
three hybrids); and water transfers from mainland China (13 species). Most of the species recorded are native to
Central and South America (27 species), East Asia (21 species), Southeast Asia (15 species), or Africa (15 species).
However, a lack of experimental or manipulative studies and a scarcity of historical data limits our understanding
of the extent of their ecological impacts. This synthesis of all currently available information could provide a
basis for future research work and policy/management strategies that seek to pre-emptively reduce the likelihood
of further species introductions to minimise potential harm to the environment.
Key words. invasive species, aquarium trade, reservoirs, aquaculture, water transfers, South China
RAFFLES BULLETIN OF ZOOLOGY 71: 128–168
Date of publication: 22 February 2023
DOI: 10.26107/RBZ-2023-0012
http://zoobank.org/urn:lsid:zoobank.org:pub:82C3DAD3-0920-4430-A93D-9F887A58DC1A
© National University of Singapore
ISSN 2345-7600 (electronic) | ISSN 0217-2445 (print)
INTRODUCTION
Hong Kong is a special administrative region of mainland
China, situated on the tropical fringe of the country’s southern
coast. It encompasses three regions: Hong Kong Island,
Kowloon peninsula, and the New Territories. While known
for its high rises and dense infrastructure, approximately
76% of Hong Kong is undeveloped, and 40% comprises
statutorily protected country parks (Environment Bureau,
2016) that are largely uninhabited. These are drained by
relatively undisturbed streams providing habitat for native
freshwater shes. Some of these streams feed into reservoirs
that lack indigenous lacustrine sh fauna, as there are no
natural lakes in the territory.
Non-native freshwater shes are becoming increasingly
widespread in Hong Kong (Tricarico et al., 2016; Tsang &
Dudgeon, 2021a), reecting similar trends across the globe
(Gozlan et al., 2010; Strayer, 2010). Non-native fishes
affect multiple levels of biological organisation (genes,
individuals, populations, communities, and ecosystems), with
notable ecological impacts including disruption of stream
food webs as well as predation of and/or competition with
native species (Cucherousset & Olden, 2011; Dudgeon,
2020). Despite this, we lack comprehensive information
about the extent of this issue (e.g., which non-native shes
are present in Hong Kong), while their impacts on local
ecosystems are not fully understood. For instance, recent
ndings suggest that poeciliids, such as Gambusia afnis
and Poecilia reticulata, can reduce the species richness of
freshwater invertebrates in mesocosms (i.e., an enclosed
articial system) and wetland eld experiments (Tsang &
Dudgeon, 2021b; Tsang & Dudgeon, 2021c), but evidence
of any clear effect on native shes in natural streams is still
lacking (Tsang & Dudgeon, 2021a).
Historically, the majority of Hong Kong’s non-native sh
species originate from aquaculture, with most recorded in
reservoirs. This includes species stocked by the government
for angling and mosquito control (Lin, 1949). However,
since 1965, raw water from the Dongjiang (East River) of
Guangdong Province in southern China has been piped to
Hong Kong to augment the local water supply (WSD, 2021),
carrying with it propagules of non-native shes (Lai, 2011).
Conservation & Ecology
Accepted by: Jeffrey T. B. Kwik
1School of Biological Sciences, The University of Hong Kong, Hong Kong;
(*corresponding authors, J.C.F. Chan, Email: jcf@freshwatercollective.org, J.H. Liew,
Email: jhliew@ln.edu.hk).
2Science Unit, Lingnan University, Hong Kong.
3School of Science and Technology, Hong Kong Metropolitan University, Hong Kong.
4aec ltd. (part of the Aurecon Group), 122-127 Commercial Centre, Palm Springs,
Yuen Long, Hong Kong.
5Lee Kong Chian Natural History Museum, National University of Singapore, 2
Conservatory Drive, Singapore 117377.
129
RAFFLES BULLETIN OF ZOOLOGY 2023
This potential introduction pathway has grown signicantly
over time, constituting 79% of total freshwater supply in
Hong Kong by 2020/2021 (WSD, 2021). Although water
from the Dongjiang itself is only channelled to two reservoirs
(e.g., Tai Lam Chung and Plover Cove Reservoirs), Hong
Kong’s reservoirs are connected by an underground tunnel
network that may facilitate the spread of non-native shes
to other localities (Dudgeon, 1996).
Another major source of non-native shes is the aquarium
trade, which peaked in Hong Kong between 1965 and 1970
when there were more than 600 ornamental sh farms often
culturing various species in outdoor ponds (Man, 1988).
Despite the industry’s subsequent decline due to competition
from mainland China (Man, 1988) and Singapore, legacy
escapees, particularly poeciliids, have established long-term
populations (Dudgeon & Corlett, 1994). Through some of
these sources (i.e., aquaculture and the aquarium trade), non-
native shes can be further dispersed through a combination
of pathways including intentional stocking, release of
unwanted pets and during religious rituals. The latter is a
common practice among Hong Kong’s Buddhists and Taoists
(Shiu & Stokes, 2008), and may be an underestimated
pathway of introduction (Magellan, 2019), especially for
freshwater shes (Chan, 2006).
The most recent comprehensive catalogue of freshwater shes
in Hong Kong was published three decades ago (Chong
& Dudgeon, 1992). Here, a total of 18 non-native species
were recorded from streams and rivers, but the tally did
not include reservoirs. A more recent survey of non-native
shes in reservoirs (Lai, 2011), recorded 26 non-native
shes. Additionally, eld guides and checklists produced
by the Agriculture, Fisheries and Conservation Department
(AFCD) of the Hong Kong Government (see Lee et al.,
2004; AFCD, 2021a; AFCD, 2021b) provide supplemental
records of non-native shes, although these accounts often
lack information about species distributions. This paper aims
to consolidate all available information about the diversity,
distribution, and plausible introduction sources of non-native
freshwater shes in Hong Kong using a combination of
literature reviews and ecological surveys.
MATERIAL AND METHODS
This checklist was compiled using data from eld surveys,
literature reviews (scientic publications and local technical
reports from 1949–2021: environmental impact assessments;
environmental permit applications; and management
agreements), and citizen science observations from the
iNaturalist platform deposited on the Global Biodiversity
Information Facility (GBIF.org, 2021). Species recorded from
literature were veried as far as possible from photographic
records, specimens, or descriptions of the species concerned
in the studies. Suspected misidentifications (i.e., single
records of species unlikely to survive in Hong Kong reported
from places where similar non-native species are known to
occur; e.g., Siluris glanis recorded in places where Clarias
gariepinus are present) that were unsupported by specimens
or photographs have been excluded. Only citizen science
observations that attained ‘research grade’ (with a date,
photograph, location coordinates, and at least two independent
conrmations of the species identication), which were also
veried by the authors, have been included in the current
study. Additional records from other sources (e.g., websites)
were included only if locality and species identity (e.g., via
clear photographs) could be conrmed.
Ad-hoc field surveys were conducted in streams, river
systems, concrete channels, ponds, marshes, reservoirs,
and ditches in agricultural and village areas around Hong
Kong between January 2018 to March 2022. A total of
128 sites (Appendix 1) were selected based on previous
publications (Chong & Dudgeon, 1992; Chan, 2001; Lai,
2011; Tsang & Dudgeon, 2021a), citizen science databases,
or environmental impact assessment reports. Each site was
surveyed at least once. Surveys were non-standardised but
comprised a minimum of one 100-metre transect. Each
transect was sampled for 30 minutes using scoop nets
(25cm × 25cm, 1–2 mm mesh size, 90cm handle length)
and cast nets (4 m diameter, 2 cm mesh size). Fish were
identied to the species-level following Pan et al. (1991)
and Chong & Dudgeon (1992). DNA barcoding of the 12S
rRNA gene was also used to verify the lineage or identity of
putative hybrids and morphologically complex genera (e.g.,
Oreochromis), respectively. We used the MiFish-U-F and
MiFish-U-R universal primers (Miya et al., 2015; Hayami et
al., 2020). For the purposes of this study, recorded species
were considered to be part of a breeding population if both
juveniles and adults of the species were observed in the same
locality. Conversely, species were categorised as ‘introduced’
if we only observed a single life stage with no evidence of
reproduction. A species was assumed to be locally extinct
if it had not been recorded for more than 20 years.
We classied all species recorded into one of three potential
sources: aquaculture; aquarium trade; and water transfer.
Species were grouped under the most likely/dominant source
for summary statistics, if more than one exists. Nevertheless,
all likely sources are listed in individual species accounts,
along with detailed description of introduction pathways
(e.g., stocking, religious release).
Ad-hoc market surveys were conducted in food sh markets
and aquarium shops in Hong Kong’s ‘Goldsh Street’ (Tung
Choi Street, Mongkok) from January 2018 to January 2022.
These market surveys focused on determining whether non-
native species that had been reported during the eld surveys
and in the literature (Chong & Dudgeon, 1992; Chan, 2001;
Lai, 2011; Tsang & Dudgeon, 2021a) were sold locally,
thus constituting a possible source of introduction. We
conjectured that a species is potentially introduced via water
transfer from the Dongjiang if non-native species observed
in reservoirs, watercourses, and water tunnels that received
water from the river, also have source populations in the
Dongjiang (based on Pan et al., 1991).
Voucher specimens were euthanised in the eld using MS-
222, in accordance with international standards (Underwood
130
Chan et al.: Non-native shes of Hong Kong
Table 1. Non-native freshwater shes of Hong Kong (95 species, including ve putative hybrids). Asterisks denote species identied
during surveys of the current study (61 species, including four putative hybrids). Region of origin is based on FishBase (Froese & Pauly,
2021), while introduction sources and status are as stipulated in the Material & Methods. Two species are listed as ‘Uncertain’ due to the
difculty of distinguishing between juveniles without comprehensive genetic work.
Order and Family Species Region of Origin Main Source Status
LEPISOSTEIFORMES
Lepisosteidae Atractosteus spatula North America Aquarium trade Introduced
Lepisosteus oculatus North America Aquarium trade Introduced
OSTEOGLOSSIFORMES
Osteoglossidae Osteoglossum bicirrhosum* Central and South America Aquarium trade Introduced
Scleropages formosus Southeast Asia Aquarium trade Introduced
Notopteridae Chitala chitala South Asia Aquarium trade Introduced
Chitala ornata* Southeast Asia Aquarium trade Introduced
CLUPEIFORMES
Engraulidae Coilia grayii* East Asia Water transfers Breeding
CYPRINIFORMES
Gyrinocheilidae Gyrinocheilus aymonieri Southeast Asia Aquarium trade Introduced
Cobitidae Misgurnus dabryanus* East Asia Aquarium trade Introduced
Cyprinidae Decorus decorus East Asia Aquaculture Extinct
Barbonymus schwanenfeldii Southeast Asia Aquarium trade Introduced
Carassius auratus* East Asia Aquarium trade Breeding
Cirrhinus molitorella* Southeast Asia Aquaculture Breeding
Cirrhinus mrigala South Asia Aquaculture Introduced
Cyprinus carpio* Europe Aquaculture Introduced
Dawkinsia denisonii* South Asia Aquarium trade Introduced
Dawkinsia lamentosa South Asia Aquarium trade Introduced
Hampala macrolepidota* Southeast Asia Aquarium trade Breeding
Labeo rohita*South Asia Aquaculture Breeding
Mylopharyngodon piceus East Asia Aquaculture Extinct
Parabramis pekinensis East Asia Water transfers Introduced
Puntigrus tetrazona* Southeast Asia Aquarium trade Introduced
Puntius titteya*South Asia Aquarium trade Introduced
Squaliobarbus curriculus East Asia Aquaculture Introduced
Xenocyprididae Chanodichthys erythropterus East Asia Water transfers Introduced
Ctenopharyngodon idella* East Asia Aquaculture Introduced
Culter recurviceps East Asia Water transfers Breeding
Hemiculter bleekeri East Asia Water transfers Extinct
Hypophthalmichthys molitrix*East Asia Aquaculture Introduced
Hypophthalmichthys nobilis* East Asia Aquaculture Introduced
Opsariichthys sp.*East Asia Water transfers Breeding
Toxabramis houdemeri East Asia Water transfers Breeding
Gobionidae Sarcocheilichthys nigripinnis East Asia Water transfers Breeding
CHARACIFORMES
Serrasalmidae Colossoma macropomum Central and South America Aquarium trade Introduced
Piaractus brachypomus Central and South America Aquarium trade Introduced
Characidae Psalidodon anisitsi* Central and South America Aquarium trade Introduced
SILURIFORMES
Loricariidae Pterygoplichthys cf. disjunctivus Central and South America Aquarium trade Breeding
Pterygoplichthys spp.*Central and South America Aquarium trade Breeding
131
RAFFLES BULLETIN OF ZOOLOGY 2023
Order and Family Species Region of Origin Main Source Status
Bagridae Tachysurus vachellii East Asia Water transfers Introduced
Tachysurus sinensis* East Asia Water transfers Breeding
Tachysurus virgatus East Asia Water transfers Introduced
Clariidae Clarias gariepinus* Africa Aquaculture Breeding
Malapteruridae Malapterurus electricus Africa Aquarium trade Breeding
Mochokidae Synodontis eupterus* Africa Aquarium trade Introduced
GOBIIFORMES
Eleotridae Oxyeleotris marmorata* Southeast Asia Aquaculture Breeding
Gobiidae Eugnathogobius siamensis Southeast Asia Water transfers Breeding
SYNBRANCHIFORMES
Synbranchidae Ophichthys cuchia* South Asia Aquaculture Breeding
ANABANTIFORMES
Anabantidae Anabas testudineus*South Asia Aquaculture Breeding
Osphronemidae Osphronemus goramy* Southeast Asia Aquarium trade Introduced
Trichopodus trichopterus* Southeast Asia Aquarium trade Introduced
Channidae Channa argus* East Asia Aquaculture Uncertain
Channa argus × Channa maculata
hybrid*
—Aquaculture Uncertain
Channa limbata* Southeast Asia Aquarium trade Breeding
Channa micropeltes* Southeast Asia Aquarium trade Breeding
Channa striata* Southeast Asia Aquaculture Breeding
CICHLIFORMES
Ambassidae Parambassis ranga* Southeast Asia Aquarium trade Breeding
Cichlidae Amphilophus citrinellus* Central and South America Aquarium trade Breeding
Amphilophus labiatus* Central and South America Aquarium trade Breeding
Astronotus ocellatus* Central and South America Aquarium trade Introduced
Cichla monoculus Central and South America Aquarium trade Introduced
Cichla temensis* Central and South America Aquarium trade Introduced
Coptodon zillii* Africa Aquaculture Breeding
Geophagus brasiliensis Central and South America Aquarium trade Introduced
Hemichromis cf. camerounensis* Africa Aquarium trade Breeding
Hemichromis fasciatus Africa Aquarium trade Introduced
Hemichromis guttatus* Africa Aquarium trade Breeding
Herichthys cf. carpintis* North America Aquarium trade Introduced
Herichthys cyanoguttatus North America Aquarium trade Introduced
Heros efasciatus Central and South America Aquarium trade Introduced
Heterotilapia buttikoferi* Africa Aquarium trade Breeding
Labidochromis caeruleus* Africa Aquarium trade Introduced
Maylandia lombardoi* Africa Aquarium trade Introduced
Melanochromis auratus Africa Aquarium trade Introduced
Mesonauta festivus Central and South America Aquarium trade Introduced
Oreochromis aureus* Africa Aquaculture Breeding
Oreochromis mossambicus* Africa Aquaculture Breeding
Oreochromis niloticus* Africa Aquaculture Breeding
Oreochromis mossambicus × O.
niloticus hybrid*
—Aquaculture Breeding
Oreochromis niloticus × O. aureus
hybrid*
—Aquaculture Introduced
Parachromis managuensis* Central and South America Aquarium trade Breeding
Pelmatolapia mariae* Africa Aquarium trade Breeding
132
Chan et al.: Non-native shes of Hong Kong
Order and Family Species Region of Origin Main Source Status
Vieja bifasciata* Central and South America Aquarium trade Breeding
Vieja fenestrata* Central and South America Aquarium trade Breeding
Vieja melanurus* Central and South America Aquarium trade Breeding
Vieja zonata Central and South America Aquarium trade Breeding
Blood-red Parrot Cichlid —Aquarium trade Introduced
Flowerhorn Cichlid*—Aquarium trade Introduced
ATHERINIFORMES
Melanotaeniidae Melanotaenia trifasciata* Australasia Aquarium trade Introduced
CYPRINODONTIFORMES
Aplocheilidae Aplocheilus lineatus* South Asia Aquarium trade Breeding
Poeciliidae Gambusia afnis* Central and South America Aquarium trade Breeding
Poecilia reticulata* Central and South America Aquarium trade Breeding
Poecilia wingei* Central and South America Aquarium trade Breeding
Poecilia salvatoris* Central and South America Aquarium trade Breeding
Poecilia sphenops Central and South America Aquarium trade Introduced
Xiphophorus hellerii* Central and South America Aquarium trade Breeding
Xiphophorus maculatus* Central and South America Aquarium trade Breeding
Xiphophorus variatus* Central and South America Aquarium trade Breeding
BELONIFORMES
Hemiramphidae Hyporhamphus intermedius* East Asia Water transfers Breeding
Xenentodon cancila South Asia Aquarium trade Breeding
CENTRARCHIFORMES
Centrarchidae Micropterus salmoides* North America Aquarium trade Breeding
& Anthony, 2020). Specimens were then brought back to
the laboratory and xed in 10% formalin for two weeks,
rinsed in tap water, and then stored in 70% ethanol. The
notation ‘[LU]’ (below the species names) indicates that
voucher specimens have been deposited in the Lingnan
University Natural History Collection (LUNHC), Hong
Kong. We provide photographs of many species along with
accounts of their distribution. All photographs were taken by
the rst author unless otherwise stated. Standard length of
specimens are listed in species accounts of all photographed
specimens deposited in the LUNHC, and other specimens
(i.e., in-situ, from the aquarium trade) where available.
Historical and present distribution of species are placed
under the ‘distribution’ heading of the species accounts.
All observation localities were listed in chronological order
(with the most recent record listed last). Records based on
specimens collected during surveys by the authors have
been denoted by ‘current survey’. Native ranges of sh
species were obtained from FishBase.org (Froese & Pauly,
2021) with the region of origin (see Table 1) placed in
parentheses for widespread species, which were based on
their most widespread native region listed on FishBase.org.
Regions were grouped biogeographically: East Asia, South
Asia, Southeast Asia, Central and South America (including
species endemic to Mexico), North America, Africa, and
Europe. All maps were produced using QGIS version 3.16.8
(QGIS.org, 2021).
RESULTS
A total of 95 species of non-native freshwater fishes
from 28 families in 15 orders were recorded (Table 1).
Sixty-two species were from ve families: Cichlidae (27
species), Cyprinidae (15 species), Poeciliidae (eight species),
Xenocyprididae (eight species), and Channidae (four species).
The remaining 33 species belonged to 23 families (Table 1).
Five non-native shes were putative hybrids: four cichlids and
a channid. Half (48) of the non-native species had breeding
populations, with cichlids being dominant with 15 species
(31% of breeding species) followed by poeciliids (seven
species, 15%), and cyprinids (four species, 8%). The three
main sources of introduction for all species and hybrids were
the aquarium trade (64 species), aquaculture (23 species),
and water transfers (13 species).
133
RAFFLES BULLETIN OF ZOOLOGY 2023
Remarks. Commonly in the aquarium trade, but breeding
has not been reported locally.
Scleropages formosus (Müller & Schlegel)
Distribution. Tai Tam Reservoir (A.C. Lam, pers. comm.,
2021; GBIF.org, 2021).
Native range. Southeast Asia.
Remarks. Highly prized in the aquarium trade and listed in
CITES Appendix 1 (CITES, 2021).
Family Notopteridae
Chitala chitala (Hamilton)
Distribution. Shing Mun Reservoir, Kowloon Reservoir,
Plover Cove Reservoir (Lai, 2011 as Nopterus chitala).
Native range. India (South Asia).
Remarks. Rare in the aquarium trade. May possibly be a
misidentication of C. ornata due to similar morphological
characteristics, which were unable to be verified in the
current study.
Chitala ornata (Gray)
Distribution. Plover Cove Reservoir (A.C. Lam, pers. comm.,
2020); Aberdeen Lower Reservoir (GBIF.org, 2021); Lai
King area (current survey).
Native range. Chao Phraya and Mekong basins across
Southeast Asia.
Order Clupeiformes
Family Engraulidae
Coilia grayii (Richardson)
Distribution. Plover Cove Reservoir (Man & Hodgkiss,
1977; Man & Hodgkiss, 1981; Lai, 2011; GBIF.org, 2021;
current survey); Tai Lam Chung Reservoir (Lai, 2011;
AFCD, 2021c).
Native range. East and South China seas, and the Indian
Ocean (East Asia).
Remarks. Based on the presence of juveniles and adults, there
is likely a breeding population at Plover Cove Reservoir. It
was rst recorded in Plover Cove Reservoir in Hong Kong
in 1967 (the year the reservoir was completed) where it
was suspected to originate from water piped from Shenzhen
Reservoir in Guangdong (Man, 1974).
INVENTORY OF NON-NATIVE FRESHWATER
FISHES
Order Lepisosteiformes
Family Lepisosteidae
Atractosteus spatula (Lacepède)
(Fig. 1)
Distribution. Ng Tung River (A.C. Lam, pers. comm.,
2017); Shing Mun Reservoir (GBIF.org, 2021).
Native range. North America.
Lepisosteus oculatus (Winchell)
Distribution. Pun Chun Yuen area (starsh_gaia, 2021).
Native range. North America.
Remarks. This was a record from iNaturalist (https://www.
inaturalist.org/observations/72235295), but has not been
included in the GBIF database due to only recently attaining
‘research grade’ recognition.
Order Osteoglossiformes
Family Osteoglossidae
Osteoglossum bicirrhosum (Cuvier)
(Fig. 2)
Fig. 1. Atractosteus spatula, aquarium trade, photographed by
Heok Hui Tan.
Fig. 2. Osteoglossum bicirrhosum, 215 mm SL, aquarium trade,
photographed by Heok Hui Tan.
Distribution. Ng Tung River, Plover Cove Reservoir (A.C.
Lam, pers. comm., 2017); Tsing Yi Park, Tai Tam Reservoir
(GBIF.org, 2021); Lai King area, Shing Mun Reservoir
(current survey).
Native range. South America.
134
Chan et al.: Non-native shes of Hong Kong
Order Cypriniformes
Family Gyrinocheilidae
Gyrinocheilus aymonieri (Tirant)
(Fig. 3, [LU])
Family Cyprinidae
Barbonymus schwanefeldii (Bleeker)
(Fig. 5)
Fig. 3. Gyrinocheilus aymonieri, 136 mm SL, aquarium trade,
photographed by Heok Hui Tan.
Distribution. Siu Lek Yuen area (GBIF.org, 2021); Plover
Cove Reservoir (H.T. Cheng, pers. comm., 2021).
Native range. Southeast Asia.
Remarks. The golden variety of this species is commonly
sold as a ‘cleaner sh’ in the aquarium trade.
Family Cobitidae
Misgurnus dabryanus (Dabry de Thiersant)
(Fig. 4, [LU])
Fig. 4. Misgurnus dabryanus, 141.6 mm SL, Shing Mun Reservoir.
Distribution. Lam Tsuen River, Siu Lek Yuen area (GBIF,
2021); Sham Tseng Settlement Basin, Tai Po Kau Nature
Reserve; Shing Mun Reservoir (current survey).
Native range. Central China, South China, and Taiwan
(East Asia).
Remarks. This species is morphologically similar to the
native Misgurnus anguillicaudatus, and has been known
to hybridise with it in the wild (You et al., 2009). DNA
sequencing of the specimen from Shing Mun Reservoir
(Fig. 18) matched with multiple P. dabryanus purebreds
and a single hybrid, suggesting the 12S RNA gene may
not be sufcient to delineate hybrids of this species. The
localities listed in the distribution also have records of M.
anguillicaudatus, which may already be hybridising in Hong
Kong. Alarmingly, M. dabryanus and M. anguillicaudatus
are commonly sold admixed as live feeder fish and are
sometimes released during Buddhist rituals. It is possible
both species hybridised in the aquarium trade before release.
Further genetic work is required to resolve this issue.
Fig. 5. Barbonymus schwanefeldii, 95.8 mm SL, aquarium
trade, photographed by Heok Hui Tan.
Distribution. Shing Mun Reservoir, Aberdeen Upper and
Lower Reservoirs (Lee et al., 2004); Lau Shui Heung
Reservoir (AFCD, 2021c).
Native range. Southeast Asia.
Carassius auratus (Linnaeus)
(Fig. 6, [LU])
Fig. 6. Carassius auratus, Little Hawaii Stream.
Distribution. Plover Cove Reservoir (Dudgeon, 1983; Lai,
2011); Sandy Ridge Cemetery, Sha Ling, Ma Dai Stream,
Cheung Po, Lin Ma Hang (Wilson et al., 1997); Nam Long
Shan area (within Ocean Park) (Maunsell Environmental
Management Consultants Limited, 2006); Fung Lok Wai
area (CH2M HILL Hong Kong Limited, 2008); Hok Tau
Reservoir (Lai, 2011); Lok Ma Chau Loop, Tse Koo Hang
area, Ma Tso Lung area (Ove Arup & Partners Hong Kong
Limited, 2013a); Ha Che area (Atkins China Limited, 2020);
Tai Po Kau Nature Reserve, Tai Lam Chung Reservoir
(AFCD, 2021c); Kam Tin River, Ho Pui River, Tong Fuk
River, Ma Wat River, Lam Tsuen River, Wong Lung Hang,
(DSD, 2021); Ng Tung River, Lai Chi Kok Park, Mui Tsz
Lam Stream, Mui Wo River, Sheung Yue River, Shui Chuen
O Stream, Tan Shan River, Shing Mun River, (GBIF.org,
2021); Tung Chung River (Green Power, 2021); Mai Po
Nature Reserve (WWF, 2021); Sam Dip Tam Stream, Kau
Lung Hang Lo Wai, Fung Yuen Stream (Tsang & Dudgeon,
2021a); Little Hawaii Stream; Lohas Park area, Deep Water
135
RAFFLES BULLETIN OF ZOOLOGY 2023
Bay Stream, Kowloon Reservoir, Miu Shan Stream (current
survey).
Native range. East Asia, including South China.
Remarks. Wild-types of this popular aquarium species were
reportedly present in lowland streams and ditches in the New
Territories during the 1940s (Lin, 1949). Their presence in
remote streams in the New Territories (e.g., Lin Ma Hang)
suggests wild-types may naturally occur in Hong Kong.
However, these may also be relict aquarium trade escapees
from breeding ponds seen in Lin (1949).
Cirrhinus molitorella (Valenciennes)
(Fig. 7, [LU])
Cyprinus carpio (Linnaeus)
(Fig. 8, [LU])
Fig. 7. Cirrhinus molitorella, 63.8 mm SL, Kowloon Reservoir.
Distribution. Plover Cove Reservoir (Dudgeon, 1983; Lai,
2011; current survey); Tai O River (Ove Arup & Partners
Hong Kong Limited, 2002; current survey); Mai Po Nature
Reserve (WWF, 2006; WWF, 2021); Hok Tau Reservoir,
Upper Shing Mun Reservoir, Kowloon Reservoir, Shek
Lei Pui Reservoir (Lai, 2011; current survey); Tung Chung
River (Green Power, 2021); Sandy Ridge area (Ove Arup
& Partners Hong Kong Limited, 2016); Lau Shui Heung
Reservoir, Tai Po Kau Nature Reserve, Tai Lam Chung
Reservoir, Tai Ho River (AFCD, 2021c); Wong Lung Hang,
Cheung Po Stream, Shek Kong Stream, Lam Tsuen River,
Ho Chung River (DSD, 2021); Mui Tsz Lam Stream, Ng
Tung River, Wu Kau Tang Stream (GBIF.org, 2021); Sam
Dip Tam Stream (Tsang & Dudgeon, 2021a); Deep Water
Bay Stream, Yung Shue O Stream, Kowloon Reception
Reservoir (current survey).
Native range. (Southeast Asia) to Vietnam and South China.
Remarks. This species was imported from Guangzhou and
introduced into the sh farms of New Territories prior to
the 1950s (Lin, 1949). It is still reared as food and sold in
local markets. Fingerlings are sold as feeder sh for large
carnivorous ornamental species and are sometimes released
during Buddhist rituals.
Cirrhinus mrigala (Hamilton)
Distribution. Wong Lung Hang, Lam Tsuen River (DSD,
2021); Ng Tung River, Ho Chung River (GBIF.org, 2021).
Native range. South Asia.
Remarks. Fingerlings are sold as feeder fish for large,
carnivorous ornamental species and are sometimes released
during Buddhist rituals.
Distribution. Sandy Ridge Cemetery (Chan, 2001; Ove
Arup & Partners Hong Kong Limited, 2016); Kam Tin
River (Black & Veatch Hong Kong Limited, 2005; current
survey); Wo Shang Wai area (Mott Connell Limited, 2008);
San Tau area (Ove Arup & Partners Hong Kong Limited,
2009); High Island Reservoir, Ho Pui Reservoir, Hok Tau
Reservoir, Shing Mun Reservoir, Kowloon Reservoir,
Kowloon Reception Reservoir, Pok Fu Lam Reservoir (Lai,
2011; current survey); Tai Lam Chung Reservoir (Lai, 2011;
AFCD, 2021c; GBIF.org, 2021; current survey); Plover Cove
Reservoir (Lai, 2011; GBIF.org, 2021); Kong Nga Po area
(Mott MacDonald Hong Kong Limited, 2013); Tai Sheung
Tok area (Ove Arup & Partners Hong Kong Limited, 2014);
Tseng Lan Shue area (Black & Veatch Hong Kong Limited,
2018); Ha Che area (Atkins China Limited, 2020); Nam Wa
Po area (DSD, 2020); Shek Kiu Tau area (Mott MacDonald
Hong Kong Limited, 2020); Shek Pik Reservoir (AFCD,
2021c); Wong Lung Hang, Shek Kong Stream, Ho Chung
River, Yuen Long Bypass Floodway, Lam Tsuen River, Ma
Wat River (DSD, 2021); Ng Tung River, Hong Kong Park,
Tin Shui Wai River, Yuen Long Park, Tin Shui Wai Park,
Kowloon Park, Wetland Park, Sheung Wo Hang Stream, Tai
Tam Byewash Reservoir, Plover Cove Reservoir (GBIF.org,
2021, as Cyrpinus carpio and Cyprinus rubrofuscus); Mai
Po Nature Reserve (WWF, 2021) ); Sham Tseng Settlement
Basin, Aberdeen Upper Reservoir, Hoi Ha Stream, Tai O
River, Yung Shue O Stream (current survey).
Native range. Black, Caspian, and Aral seas basins, Europe.
Remarks. Only Cyprinus carpio has been recorded in
the results of our DNA barcoding despite citizen science
suggesting the presence of both C. carpio and C. rubrofuscus.
The latter is not considered to occur in Hong Kong until
genetic evidence is obtained. Wild-types are most commonly
encountered in Hong Kong’s fresh waters and likely originate
from aquaculture while the ornamental variety originate from
the aquarium trade, with the latter now becoming increasingly
Fig. 8. Cyprinus carpio wild type, 307 mm SL, Tai O River (top),
ornamental variety, 596mm SL, Shing Mun Reservoir (bottom).
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Chan et al.: Non-native shes of Hong Kong
common in village streams. Juvenile ornamental varieties
are sometimes released during Buddhist rituals.
Dawkinsia denisonii (Day)
Distribution. Wong Lung Hang Stream (current survey).
Native range. South Asia.
Remarks. Common in the aquarium trade.
Dawkinsia lamentosa (Valenciennes)
Distribution. Kowloon Reservoir (Lai, 2011 as Puntius
lamentosus); Aberdeen Lower Reservoir (GBIF.org, 2021).
Native range. South Asia.
Decorus decorus (Peters)
Distribution. Kau Sai Chau area (Wilson et al., 1997 as
Bangana decora).
Native range. Endemic to the Xijiang (West River), South
China (East Asia).
Remarks. A single individual reported was likely mixed-up
with other aquacultured sh that were released into ponds in
the Kau Sai Chau Golf Course (Wilson et al., 1997). It has
not been observed in Hong Kong since its initial discovery
and is considered to be locally extinct.
Hampala macrolepidota (Kuhl & Van Hasselt)
(Fig. 9, [LU])
Labeo rohita (Hamilton)
Distribution. Ho Chung River, Ng Tung River, Shing
Mun Reservoir (GBIF.org, 2021); Plover Cove Reservoir
(current survey).
Native range. (South Asia), Myanmar, Southeast Asia.
Remarks. Commonly found in the aquarium trade (as
ngerlings and often mixed with Cirrhinus spp.) as food
for large, carnivorous shes.
Mylopharyngodon piceus (Richardson)
Distribution. Unknown.
Native range. Amur River basin to South China (East Asia).
Remarks. Listed as an uncommon pond fish by Man
& Hodgkiss (1981) with no notes on exact localities. It
was likely an escapee from an aquaculture facility, and
is presumably no longer present since there have been no
subsequent records (Chong & Dudgeon, 1992).
Parabramis pekinensis (Basilewsky)
Distribution. Tai Lam Chung Reservoir (Lai, 2011).
Native range. Amur River basin to East China (East Asia).
Remarks. Restricted to a single reservoir that receives water
from the Dongjiang. Previously, it has been cultivated in
shponds (Man & Hodgkiss, 1981), suggesting it may also
have individuals released from aquaculture.
Puntigrus tetrazona (Bleeker)
(Fig. 10, [LU])
Distribution. Shing Mun Reservoir (GBIF.org, 2021; current
survey); Lower Shing Mun Reservoir (current survey).
Native range. Southeast Asia.
Remarks. Large individuals (over 30cm TL) have been
observed to have penetrated as far as the middle reaches
of hill streams that ow into Shing Mun Reservoir during
the wet season.
Distribution. Kowloon Reception Reservoir (C.Y. Tse,
pers. comm., 2020); Plover Cove Reservoir (current survey).
Native range. Southeast Asia.
Remarks. Common in the aquarium trade.
Fig. 9. Hampala macrolepidota, 49 mm SL, Lower Shing Mun
Reservoir.
Fig. 10. Puntigrus tetrazona, 35 mm SL, Plover Cove Reservoir.
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Puntius titteya (Bleeker)
(Fig. 11, [LU])
GBIF.org, 2021); Lam Tsuen River, Sheung Yue River, Ng
Tung River (GBIF.org, 2021).
Native range. South China, East Asia.
Remarks. This species may have also been accidentally
introduced during sh stocking of reservoirs (Lai, 2011).
Hemiculter bleekeri (Warpachowski)
Distribution. Plover Cove Reservoir (Man & Hodgkiss,
1977; Dudgeon, 1983).
Native range. Central and South China, East Asia.
Remarks. Reportedly introduced into Plover Cove Reservoir
from “various rivers” through water transfer in 1967 (Man
& Hodgkiss, 1977). This species has not been reported since
Dudgeon (1983) and is presumably locally extinct.
Hypophthalmichthys molitrix (Valenciennes)
(Fig. 12, [LU])
Distribution. Shing Mun River, Sandy Ridge Cemetery
(Chan, 2001); Kam Tin River (A.C. Lam, pers. comm.,
2015); Tai Lam Chung Reservoir (AFCD, 2021c); Ng Tung
River, Sheung Yue River (GBIF.org, 2021); Pak Ngau Shek
Stream (current survey).
Native range. China and Vietnam (East Asia).
Remarks. Juveniles are regularly stocked (suspected to be
from aquaculture) in (unspecied) reservoirs to control algae
as they are believed to be incapable of reproducing in Hong
Kong’s fresh waters (WSD, 2019).
Hypophthalmichthys nobilis (Richardson)
(Fig. 13)
Fig. 13. Hypophthalmichthys nobilis, aquarium trade, photographed
by Heok Hui Tan.
Fig. 11. Puntius titteya, 17.3 mm SL, Black Hill, note damaged
caudal n.
Distribution. Black Hill (current survey).
Native range. South Asia.
Remarks. Common in the aquarium trade.
Squaliobarbus curriculus (Richardson)
Distribution. Ng Tung River, Tai Ho River (GBIF.org, 2021).
Native range. Amur river basin to Vietnam (East Asia).
Family Xenocyprididae
Chanodichthys erythropterus (Basilewsky)
Distribution. Plover Cove Reservoir (Man & Hodgkiss,
1981 as Culter erythropterus; Dudgeon, 1983 as Culter
erythropterus; Chong & Dudgeon, 1992 as Culter
erythropterus; Lai, 2011 as Cultrichthys erythropterus);
Tai Lam Chung Reservoir (AFCD, 2021c).
Native range. East Asia.
Remarks. Restricted to reservoirs that receive water from
mainland China.
Ctenopharyngodon idella (Valenciennes)
Distribution. Tai Ho River (Chan, 2001 as Ctenopharyngodon
idellus; AFCD, 2021c); Lok Ma Chau Loop (Ove Arup &
Partners Hong Kong Limited, 2013a); Hok Tau Reservoir
(AFCD, 2021c; current survey); Ho Chung River (DSD,
2021; current survey); Ng Tung River, Sheung Yue River,
Long Valley, Hong Kong Wetland Park (GBIF.org, 2021);
Mai Po Nature Reserve (WWF, 2021).
Native range. East China and Russia (East Asia).
Remarks. Actively farmed in aquaculture ponds in the New
Territories. It is sometimes released during Buddhist rituals,
presumably after having been purchased from wet markets.
Culter recurviceps (Richardson)
Distribution. Kowloon Reception Reservoir, Tai Lam Chung
Reservoir (Lai, 2011); Plover Cove Reservoir (Lai, 2011;
Fig. 12. Hypophthalmichthys molitrix, 52 mm SL, Pak Ngau Shek
Stream.
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Chan et al.: Non-native shes of Hong Kong
Distribution. Kau Sai Chau, Aberdeen Upper Reservoir, High
Island Reservoir (Lee et al., 2004), Plover Cove Reservoir
(Lee et al., 2004, GBIF.org, 2021); Kam Tin River (A.C.
Lam, pers. comm., 2015); Tai Lam Chung Reservoir (AFCD,
2021c); Yuen Long Bypass Floodway (DSD, 2021); Wetland
Park (GBIF.org, 2021); Tung Chung River (Green Power,
2021); Lam Tsuen River (current survey).
Native range. China, East Asia.
Remarks. As with Hypophthalmichthys molitrix, juveniles of
this species are regularly stocked in reservoirs (WSD, 2019).
Opsariichthys sp. (Günther)
(Fig. 14, [LU])
Distribution. Tai Lam Chung Reservoir (Wilson et al., 1997
as Opsariichthys bidens; Lai, 2011 as Opsariichthys bidens;
AFCD, 2021c as Opsariichthys bidens; current survey).
Native range. East Asia.
Remarks. Restricted to a single reservoir that receives
water from mainland China. DNA barcoding has indicated
this species is not Opsariichthys bidens, but instead groups
with an unnamed Opsariichthys sp. deposited on GenBank
(accession number: KJ913670). It is not known where the
specimen on GenBank originated from. Further taxonomic
work is required to identify this species.
Toxabramis houdemeri (Pellegrin)
Distribution. Kowloon Reception Reservoir (Lai, 2011);
Plover Cove Reservoir (H.T. Cheng, pers. comm., 2021).
Native range. China and Vietnam (East Asia).
Remarks. Restricted to reservoirs that receive water piped
from mainland China
Family Gobionidae
Sarcocheilichthys nigripinnis (Günther)
Distribution. Plover Cove Reservoir, Tai Lam Chung
Reservoir (GBIF, 2021; H.T. Cheng, pers. comm., 2021).
Native range. East China, South China, Taiwan and Korea
(East Asia).
Fig. 14. Opsariichthys sp., 93.5 mm SL, Tai Lam Chung Reservoir. Fig. 15. Colossoma macropomum, 295 mm SL, aquarium trade,
photographed by Heok Hui Tan.
Distribution. Ho Chung River, Lions Nature Education
Centre (GBIF.org, 2021).
Native range. Central and South America.
Piaractus brachypomus (Cuvier)
Distribution. Ng Tung River (A.C. Lam, pers. comm., 2017).
Native range. Central and South America.
Family Characidae
Psalidodon anisitsi (Eigenmann)
Distribution. Deep Water Bay Stream (current survey).
Native range. Central and South America.
Remarks. Common in the aquarium trade.
Order Siluriformes
Family Loricariidae
Pterygoplichthys cf. disjunctivus (Weber)
Distribution. Lam Tsuen River; Ma Wat River (DSD, 2021);
Ng Tung River (GBIF.org, 2021).
Native range. Central and South America.
Remarks. Restricted to reservoirs that receive raw water
piped from mainland China.
Order Characiformes
Family Serrasalmidae
Colossoma macropomum (Cuvier)
(Fig. 15)
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Pterygoplichthys spp.
(Fig. 16.)
Tachysurus virgatus (Oshima)
Distribution. Man Kam To area (Chan & Ho, 2011).
Native range. China and Vietnam (East Asia).
Remarks. The locality where this species has been recorded
in receives water from mainland China via transfer pipes
(Chan & Ho, 2011).
Family Clariidae
Clarias gariepinus (Burchell)
(Fig. 17)
Fig. 16. Pterygoplichthys sp., Lam Tsuen River, photographed by
Tommy C.H. Hui.
Distribution. Plover Cove Reservoir, Kowloon Reception
Reservoir (Lai, 2011); Ho Chung River (DSD, 2021); Ng
Tung River (GBIF.org, 2021); Ko Po area (Fanling); Kam
Tin River, Tin Shui Wai River, Aberdeen Upper Reservoir,
Aberdeen Lower Reservoir, Kowloon Reservoir, Kowloon
Byewash Reservoir, Tai Lam Chung Reservoir, Shing
Mun Reservoir, Lower Shing Mun Reservoir, Pok Fu Lam
Reservoir, Wong Nai Chung Reservoir, Tai Tam Byewash
Reservoir, Tsing Tam Reservoir, High Island Reservoir
(H.T. Cheng, pers. comm., 2021); Tan Shan River, Tung
Tsz Stream, Lam Tsuen River (current survey).
Native range. Central and South America.
Remarks. These records might comprise several species,
which are not identiable to species level due to complex
taxonomy and hybridisation (Wu et al., 2011).
Family Bagridae
Tachysurus vachellii (Richardson)
Distribution. Man Kam To area (Chan & Ho, 2011 as
Pseudobagrus vachellii); Sheung Yue River (GBIF.org,
2021).
Native range. China and Vietnam (East Asia).
Remarks. The localities where this species has been recorded
are connected to mainland China water transfer outlets (Chan
& Ho, 2011).
Tachysurus sinensis (Richardson)
Distribution. Tai Lam Chung Reservoir (GBIF.org, 2021;
current survey).
Native range. China and Korea (East Asia).
Remarks. Restricted to reservoirs that receive water from
the mainland. It is also commonly sold in wet markets,
which may represent an additional source of introductions
from aquaculture.
Fig. 17. Clarias gariepinus, 916 mm SL, Waterfall Bay Stream,
photographed by Samuel C.L. Ho.
Distribution. Sandy Ridge Cemetery (Chan, 2001); Kam Tin
River (Black & Veatch Hong Kong Limited, 2005; DSD,
2021; current survey); Nam Long Shan area (within Ocean
Park) (Maunsell Environmental Management Consultants
Limited, 2006); Kowloon Reservoir (Lai, 2011; current
survey); Yuen Long Town Nullah (Black & Veatch Hong
Kong Limited, 2020a); Nam Wa Po area (DSD, 2020; GBIF.
org, 2021); Lok Ma Chau area (Ove Arup & Partners Hong
Kong Limited, 2013a); Ho Chung River, Ping Yuen River,
Yuen Long Bypass Floodway, Ngau Tam Mei River, Ping
Kong Stream, Ho Pui River, Ma Wat River (DSD, 2021)
Lin Ma Hang Stream, Ma Tso Lung area, Wong Yue Tan
area, Sheung Yue River, Hung Leng Tsuen area, Shan Pui
River, Long Valley (GBIF.org, 2021); Tin Shui Wai River,
Mui Wo area, Pui O Stream, Tai Ho River, Jordan Valley
(H.T. Cheng, pers. comm., 2021); Mai Po Nature Reserve
(WWF, 2021); Waterfall Bay Stream, Ng Tung River, Kai
Tak River (current survey).
Native range. Africa.
Remarks. This species thrives in rivers polluted by organic
waste in the New Territories.
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Family Malapteruridae
Malapterurus electricus (Gmelin)
Distribution. Kowloon Reservoir (Lai, 2011).
Native range. Africa.
Remarks. Breeding populations were discovered by Lai
(2011) in Kowloon Reservoir, but none were observed
during the current study.
Family Mochokidae
Synodontis eupterus (Boulenger)
(Fig. 18, [LU])
Shing Mun Reservoir, Lam Tei Irrigation Reservoir, Hung
Shui Hang Irrigation Reservoir (current survey).
Native range. (Southeast Asia) and South Asia.
Remarks. Commonly sold in wet markets and is a local
delicacy.
Family Gobiidae
Eugnathogobius siamensis (Fowler)
Distribution. Plover Cove Reservoir (GBIF.org, 2021); Tai
Lam Chung Reservoir (H.T. Cheng, pers. comm., 2021).
Native range. (Southeast Asia) and South China.
Remarks. Restricted to reservoirs that receive raw water
from mainland China but not known from the Dongjiang
and adjacent river systems, although it may have been
overlooked because of its tiny size (≤ 40 mm TL (Froese
& Pauly, 2021)). This goby is neither in the aquarium trade
nor used in aquaculture. It has been recorded from Lai Chi
Wo estuary in the New Territories, Hong Kong (Larson,
2009), but has not been reported from South China or Hong
Kong since and does not appear to be represented by native
populations in Hong Kong.
Order Synbranchiformes
Family Synbranchidae
Ophichthys cuchia (Hamilton)
(Fig. 20)
Fig. 18. Synodontis eupterus, 112.6 mm SL, Tai Po Kau Nature
Reserve.
Distribution. Tai Po Kau Nature Reserve (current survey).
Native range. Africa.
Remarks. Juveniles are often present in the aquarium trade.
Order Gobiiformes
Family Eleotridae
Oxyeleotris marmorata (Bleeker)
(Fig. 19, [LU])
Fig. 19. Oxyeleotris marmorata, 138 mm SL, Lau Shui Heung
Irrigation Reservoir.
Distribution. Plover Cove Reservoir (Lai, 2011; current
survey); Kowloon Reservoir (GBIF.org, 2021; current
survey); Tai Lam Chung Reservoir, Lau Shui Heung
Reservoir; Hok Tau Reservoir, Shing Mun Reservoir, Lower
Fig. 20. Ophichthys cuchia, Lau Shui Heung Reservoir, photographed
by Tommy C.H. Hui.
Distribution. Lui Kung Tin area, Ng Tung River (GBIF.
org, 2021); Lau Shui Heung Reservoir, Wong Nai Chung
Reservoir, Plover Cove Reservoir (current survey).
Native range. (South Asia) and Southeast Asia.
Remarks. Commonly sold as food in wet markets and is
sometimes released during Buddhist rituals.
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Order Anabantiformes
Family Anabantidae
Anabas testudineus (Bloch)
(Fig. 21, [LU])
Family Channidae
Channa argus (Cantor)
(Fig. 22A)
Fig. 21. Anabas testudineus, 70.7 mm SL, Shui Hau Stream.
Distribution. Lok Ma Chau area (Ove Arup & Partners
Hong Kong Limited, 2013a; current survey); Tsung Yuen
Stream, Long Valley area (Ove Arup & Partners Hong Kong
Limited, 2013b); Nam Sang Wai area (Black & Veatch Hong
Kong Limited, 2020a; current survey); Tung Chung River,
Ma Tso Lung Stream (DSD, 2021); Tai Ho River, Shek
Pik Reservoir, Tai O area, Mai Po Nature Reserve, Pui O
Stream, Shui Lo Cho Stream, Sandy Ridge Cemetery area
(GBIF.org, 2021); Tsing Tai Stream, Shui Hau Stream, Mui
Wo area (current survey).
Native range. (South Asia), Southeast Asia, and China.
Remarks. Many breeding populations are found in the
northern New Territories and some parts of Lantau Island,
where they occur in stagnant waters. During heavy rain, they
have been observed attempting to colonise new habitats by
travelling across the inundated terrestrial landscape.
Family Osphronemidae
Osphronemus goramy (Lacepède)
Distribution. Wong Nai Chung Reservoir, Shing Mun
Reservoir (current survey).
Native range. Southeast Asia.
Remarks. Common in the aquarium trade.
Trichopodus trichopterus (Pallas)
Distribution. Tai Po Kau Nature Reserve (current survey).
Native range. (Southeast Asia) and South Asia.
Remarks. A single individual was observed in a man-made
pond in the Reserve in 2020.
Fig. 22. A, Channa argus, Ng Tung River, Channa maculata,
B1, (dorsal head pattern), B2, (lateral pattern), She Shan River
(uncertain origin), Channa argus × Channa maculata hybrid, C1,
(dorsal head pattern), C2, (lateral pattern), Ng Tung River.
Distribution. Ng Tung River (GBIF.org, 2021); Kowloon
Reservoir; Tai Lam Chung Reservoir (current survey).
Native range. Amur River Basin to South China (East Asia).
Remarks. This species is occasionally sold together with
Channa maculata and Channa argus × Channa maculata
hybrids in local wet markets. Channa argus is bigger than
C. maculata, with larger lateral blotches and a well-separated
dorsal head pattern (Fig. 22A, B1) between the eyes (Ou et
al., 2018). Morphometrics cannot adequately differentiate
between juveniles of C. argus, C. maculata, and C. argus ×
C. maculata hybrids in Hong Kong. A region-wide integrative
taxonomic assessment is necessary to adequately understand
the scale of introductions, breeding, and hybridisation of
native and non-native channids. This species is sometimes
released during Buddhist rituals.
Channa argus × Channa maculata hybrid
(Fig. 22C)
Distribution. Shing Mun Reservoir, Lower Shing Mun
Reservoir, Ng Tung River, Kam Tin River, Ma Wat River,
Sheung Yue River (current survey).
Remarks. Identication solely using morphometrics have
not been reliable in Hong Kong, as putative hybrids that
matched descriptions from Ou et al. (2018) that were DNA
barcoded were identied as purebred Channa argus. The
localities listed above are a tentative distribution of this
putative hybrid whilst a comprehensive integrative taxonomic
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Chan et al.: Non-native shes of Hong Kong
assessment is pending. This species is sometimes released
during Buddhist rituals.
Channa limbata (Cuvier)
(Fig. 23, [LU])
Channa striata (Bloch)
(Fig. 24, [LU])
Distribution. Lok Ma Chau area, Ho Hok Wai area, Tse
Koo Hang area (Ove Arup & Partners Hong Kong Limited,
2013a); Tsung Yuen Stream (Ove Arup & Partners Hong
Kong Limited, 2013b); Sandy Ridge area (Ove Arup &
Partners Hong Kong Limited, 2016); Shan Ha Tsuen area
(Ove Arup & Partners Hong Kong Limited, 2017); Sung
Shan New Village (Atkins China Limited, 2020); Ping
Kong Stream, Ho Pui River, Ma Tso Lung Stream, Yuen
Long Bypass Floodway, Kam Tin River, Ping Yuen River
(DSD, 2021); Lai Chi Chong area (H.T. Cheng, pers. comm.,
2021); Fanling area, San Tin area, Tai Mei Tuk area, Nam
Sang Wai, Hoi Ha Stream, San Tau Stream (current survey).
Native range. Southeast Asia.
Remarks. First recorded by Chan (1999) as a native species
but subsequently considered to be non-native by AFCD
(2021b). Individuals are restricted to sewage channels and
degraded stream sections of continental New Territories
except for a single individual recorded in the concretised
canal of San Tau Stream, Lantau Island. Morphological and
genetic analyses by Conte-grand et al. (2017) uncovered that
specimens from Hong Kong overlap with a large number
of other Channa gachua-type shes from east of the Indo-
Burma region, including several localities in mainland China.
It is currently in a species complex with two widespread
lineages, separated by being located east (Channa limbata)
and west (C. gachua) of the Indo-Burma region. Hence, C.
limbata should be used in preference to the name C. gachua
for individuals in Hong Kong
Channa micropeltes (Cuvier)
Distribution. Tai Tam Reservoir (AC Lam, pers. comm.,
2018); Tai Tam Tuk Reservoir (GBIF.org, 2021; current
survey).
Native range. Southeast Asia.
Remarks. Juveniles are occasionally present in the aquarium
trade.
Fig. 23. Channa limbata, Fanling area.
Fig. 24. Channa striata, 220 mm SL, Pui O Stream.
Distribution. Lin Ma Hang Stream, Sha Ling area (Chan,
2001); Tai Tong area (Chan, 2001; Ove Arup & Partners
Hong Kong Limited, 2017); Man Uk Pin Stream (Black &
Veatch Hong Kong Limited, 2007); Wo Shang Wai area
(Mott Connell Limited, 2008); Lok Ma Chau Loop, Ho
Hok Wai area (Ove Arup & Partners Hong Kong Limited,
2013a); Ma Wat River, Fung Kong Stream, Tsung Yuen
Stream, Long Valley area (Ove Arup & Partners Hong Kong
Limited, 2013b); Fung Lok Wai area (CH2M HILL Hong
Kong Limited, 2008); Ping Kong Stream, Ma Tso Lung
Stream (DSD, 2021); Pui O Stream, Mai Po area, Pak Tam
Chung Stream, Tai O area, Ng Tung River, San Tin area,
Sheung Yue River, Ha Shan Kai Wat area, Sandy Ridge
Cemetery, Shui Lo Cho Stream, Shan Pui River (GBIF.org,
2021); Pak Long Stream (Tsang & Dudgeon, 2021a); Kam
Tin River, Wetland Park, Nam Sang Wai area, Tsing Tai
Stream, Yuen Long Bypass Floodway, Mui Wo area, Yi O
Stream (current survey).
Native range. South China to (Southeast Asia) and South Asia.
Remarks. Abundant and widespread in the northern New
Territories; sought-after by anglers.
Order Cichliformes
Family Ambassidae
Parambassis ranga
(Fig. 25, [LU])
Fig. 25. Parambassis ranga, 37.5 mm SL, Kowloon Reception
Reservoir.
Distribution. Kowloon Reception Reservoir (Lai, 2011 as
Chanda sp.; current survey); Plover Cove Reservoir (GBIF.
org, 2021; current survey); Tai Lam Chung Reservoir
(current survey).
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Native range. (Southeast Asia) and South Asia.
Remarks. Popular aquarium sh, often sold injected with
uorescent dye.
Family Cichlidae
Amphilophus citrinellus (Günther)
(Fig. 26, [LU])
Native range. Central and South America.
Remarks. Popular in the aquarium trade; frequently released
in urban ponds. However, breeding populations have never
been observed in Hong Kong.
Cichla monoculus (Spix & Agassiz)
Distribution. Shing Mun Reservoir; Kowloon Reservoir
(GBIF.org, 2021).
Native range. Central and South America.
Cichla temensis (Humboldt)
Distribution. Shing Mun Reservoir (current survey).
Native range. Central and South America.
Coptodon zillii (Gervais)
(Fig. 28, [LU])
Fig. 26. Amphilophus citrinellus, 79.2 mm SL, Plover Cove
Reservoir.
Distribution. Plover Cove Reservoir (GBIF.org, 2021;
current survey).
Native range. Central and South America.
Remarks. Common in the aquarium trade.
Amphilophus labiatus (Günther)
Distribution. Plover Cove Reservoir (GBIF.org, 2021;
current survey).
Native range. Central and South America.
Remarks. Breeding populations found in Plover Cove
Reservoir but not as abundant as Amphilophus citrinellus.
Astronotus ocellatus (Agassiz)
(Fig. 27)
Fig. 27. Astronotus ocellatus, Lai King area.
Distribution. Black Hill area, Kowloon Reservoir, Plover
Cove Reservoir (GBIF.org, 2021); Shing Mun Reservoir;
Lai King area (current survey).
Fig. 28. Coptodon zillii, 102.2 mm SL, Deep Water Bay Stream.
Distribution. Shing Mun River (Chan, 2001 as Tilapia
zillii); High Island Reservoir, Hok Tau Reservoir, Kowloon
Reservoir, Lau Shui Heung Reservoir, Plover Cove Reservoir,
Pok Fu Lam Reservoir, Kowloon Reception Reservoir, Shek
Lei Pui Reservoir, Tai Lam Chung Reservoir (Lai, 2011 as
Tilapia zillii); Lok Ma Chau Loop, Tse Koo Hang area (Ove
Arup & Partners Hong Kong Limited, 2013a as Tilapia zillii);
Sham Wat River (Mott MacDonald Hong Kong Limited,
2014 as Tilapia zillii); Sandy Ridge Cemetery (Ove Arup
& Partners Hong Kong Limited, 2016 as Tilapia zillii); Lin
Fa Tei area (Atkins China Limited, 2020); Nam Sang Wai
area (Black & Veatch Hong Kong Limited, 2020a; current
survey); Shek Pik Reservoir (AFCD, 2021c); Ma Tso Lung
Stream, Ping Yuen River, Yuen Long Bypass Floodway, Ho
Chung River, Ma Wat River, Lam Tsuen River, Pak Ngan
Heung Stream (DSD, 2021 as Tilapia zillii); Tung Chung
River (Green Power, 2021); Wetland Park, Shui Lo Cho
Stream, Pui O Stream, Shek Lei Pui Reservoir, Shap Long
Irrigation Reservoir, Lamma Island area, Ting Kok area, Tai
Tam Byewash Reservoir, Tan Shan River, Tai Ho River, Hang
Hau Man Kuk Lane Park (GBIF.org, 2021); Deep Water Bay
Stream, San Tin area, Ng Tung River, Sheung Yue River,
Kam Tin River, Tsing Tai Stream, Shing Mun Reservoir,
Lower Shing Mun Reservoir, Lam Tei Irrigation Reservoir,
Hung Shui Hang Irrigation Reservoir, Kowloon Byewash
Reservoir, Tai Tam Tuk Reservoir, Tai Tam Reservoir, Tai
Tam Intermediate Reservoir (current survey).
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Native range. Africa.
Remarks. One of the most widespread cichlids in Hong
Kong, thriving in both degraded lowland streams and pristine
hill streams. Abundant in reservoirs where they are now
found in greater numbers than Oreochromis spp.
Geophagus brasiliensis (Quoy & Gaimard)
Distribution. Shing Mun Reservoir (GBIF.org, 2021).
Native range. Central and South America.
Hemichromis cf. camerounensis (Bitja-Nyom, Agnèse,
Pariselle, Bilong-Bilong, Gilles & Snoeks)
(Fig. 29, [LU])
Distribution. Kowloon Reservoir, Kowloon Reception
Reservoir, Kowloon Byewash Reservoir (Mott MacDonald
Hong Kong Limited, 2008 as Hemichromis stellifer; current
survey); Tai O River (Atkins China Limited, 2016 as
Hemichromis stellifer; Tsang & Dudgeon, 2021a; current
survey); Tai Tong area (Ove Arup & Partners Hong Kong
Limited, 2017 as Hemichromis stellifer); Tai Lam Chung
Reservoir (AFCD, 2021c as Hemichromis stellifer; current
survey); Pui O Stream, Lam Tsuen River (DSD, 2021 as
Hemichromis stellifer; current survey); Tung Chung River
(DSD, 2021 as Hemichromis stellifer; Green Power, 2021;
current survey); Mui Tsz Lam Stream, Aberdeen Lower
Reservoir, Shing Mun River (GBIF.org, 2021); Wong Lung
Hang Stream, Sha Lo Wan Stream, Sham Wat River, Pak Tin
area (Tai Wai) (Tsang & Dudgeon, 2021a as Hemichromis
stellifer); Deep Water Bay Stream, San Tau Stream, Tai
Tam Tuk Reservoir, Tai Tam Reservoir, Tai Tam Byewash
Reservoir, Tai Tam Intermediate Reservoir, Wong Nai Chung
Reservoir, Lam Tei Irrigation Reservoir, Hung Shui Hang
Irrigation Reservoir, Hok Tau Reservoir, Lau Shui Heung
Reservoir, Aberdeen Upper Reservoir, Pok Fu Lam Reservoir,
Lower Shing Mun Reservoir, Shing Mun Reservoir, Shek
Lei Pui Reservoir (current survey).
Native range. Africa.
Remarks. Previously misidentied as Hemichromis stellifer
in Hong Kong. It occupies a wide range of habitats but tends
to thrive in unpolluted and well-oxygenated streams. Unlike
most other non-native sh species, Hemichromis guttatus has
penetrated further upstream (over 150 m above sea level),
in a similar manner to Xiphophorus hellerii.
Herichthys cf. carpintis (Jordan & Snyder)
(Fig. 31.)
Fig. 29. Hemichromis camerounensis, 86.4 mm SL, Lower Aberdeen
Reservoir.
Distribution. Lower Aberdeen Reservoir (GBIF.org, 2021;
current survey); Upper Aberdeen Reservoir (current survey).
Native range. Africa.
Remarks. Identied as the newly described Hemichromis
cf. camerounensis due to the presence of two red opercular
spots accompanied by a large black spot, separating it from
all other Hemichromis species (Bitja-Nyom et al., 2021).
However, DNA barcoding of the cytochrome b gene is
necessary to conrm its identity, as some populations of
Hemichromis elongatus are known to have the same feature
(Bitja-Nyom et al., 2021).
Hemichromis fasciatus (Peters)
Distribution. Tai Lam Chung Reservoir (AFCD, 2021c).
Native range. Africa.
Hemichromis guttatus (Günther)
(Fig. 30, [LU])
Fig. 30. Hemichromis guttatus, 66 mm SL, Tai Tam Tuk Reservoir.
Fig. 31. Herichthys cf. carpintis, Shing Mun Reservoir.
Distribution. Shing Mun Reservoir (current survey).
Native range. North America.
Remarks. The individual recorded from Shing Mun Reservoir
resembles a variant of the ‘Aztec’ strain Herichthys carpintis,
but DNA barcoding was inconclusive. Barcoding of other
genes is necessary for condent species identication.
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Herichthys cyanoguttatus (Baird & Girard)
Distribution. Kai Tak River (GBIF.org, 2021).
Native range. Texas, North America.
Heros efasciatus (Heckel)
Distribution. Aberdeen Lower Reservoir (GBIF.org, 2021).
Native range. Central and South America.
Heterotilapia buttikoferi (Hubrecht)
(Fig. 32, [LU])
Melanochromis auratus (Boulenger)
Distribution. Unknown.
Native range. Africa (Lake Malawi endemic).
Remarks. No location data was provided by AFCD (2021a).
Mesonauta festivus (Heckel)
Distribution. Aberdeen Lower Reservoir (GBIF.org, 2021).
Native range. Central and South America.
Oreochromis aureus (Steindachner)
(Fig. 33 [LU])
Fig. 32. Heterotilapia buttikoferi, 93.9 mm SL, Tai Tam Tuk
Reservoir.
Distribution. Kowloon Byewash Reservoir (Mott MacDonald
Hong Kong Limited, 2008 as Tilapia joka; current survey);
Plover Cove Reservoir (Lai, 2011 as Tilapia buttikoferi;
GBIF.org, 2021; current survey); Lai Chi Kok Park, Aberdeen
Lower Reservoir, Tai Tam Tuk Reservoir, Shing Mun
Reservoir (GBIF.org, 2021; current survey); Lok Ma Chau
area, Aberdeen Upper Reservoir (current survey).
Native range. Africa.
Labidochromis caeruleus (Fryer)
Distribution. Plover Cove Reservoir; Kowloon Reservoir
(current survey).
Native range. Africa (Lake Malawi endemic).
Remarks. One of the most commonly sold ornamental
cichlids in Hong Kong. However, they are rarely recorded
in the wild.
Maylandia lombardoi (Burgess)
Distribution. Shing Mun Reservoir (current survey).
Native range. Africa (Lake Malawi endemic).
Remarks. As with Labidochromis caeruleus, it is one of
the most commonly sold ornamental cichlids in Hong Kong,
but is rarely recorded in the wild.
Fig. 33. Oreochromis aureus, 330.1 mm SL, Tung Tsz Stream.
Distribution. She Shan River, Lai Chi Kok Park (GBIF.
org, 2021); Tung Tsz Stream (current survey)
Native range. Africa.
Remarks. Not as widespread as other Oreochromis spp.,
but the frequency of records has risen in recent years. It
differs from the morphologically similar Oreochromis
niloticus by having faint variable bars on the caudal n as
opposed to regular dark vertical bar, and pink-red margins
(Trewavas, 1983). Juveniles have a black spot at the rear of
the dorsal n, which is absent in Oreochromis niloticus (Gu
et al., 2016). This species may also resemble Oreochromis
niloticus × Oreochromis mossambicus hybrids, which can
be preliminarily differentiated from them by the presence of
blue spots on the dorsal and caudal ns and blue colouration
of the snout in Oreochromis aureus.
Oreochromis mossambicus (Peters)
(Fig. 34, [LU])
Fig. 34. Oreochromis mossambicus, breeding males, Ting Kok
area, photographed by Tommy C.H. Hui.
Distribution. Plover Cove Reservoir (Man & Hodgkiss,
1977 as Sarotherodon mossambicus; Man & Hodgkiss,
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Chan et al.: Non-native shes of Hong Kong
1981 as Sarotherodon mossambicus; Dudgeon, 1983 as
Sarotherodon mossambicus) Lamma Island area, Luk Keng
area, Pui O area, Sham Chung area, Sha Lo Tung area
(Dudgeon & Chan, 1996 as Sarotherodon mossambicus);
Lok Ma Chau area, San Tin area (Environmental Resources
Management Hong Kong Limited, 1999a as Sarotherodon
mossambicus); Lam Tei area (Environmental Resources
Management Hong Kong Limited, 1999b as Sarotherodon
mossambicus); Pun Chun Yuen Stream, Lam Tsuen River
(Mott Connell Limited, 2000 as Sarotherodon mossambicus);
Tai Chung Hau area, Shuen Wan area, Lin Ma Hang Stream,
Sandy Ridge Cemetery, Sha Ling area, Loi Tung area,
Sheung Wo Hang, Tai Tong area, Cheung Po Stream, Wang
Tong area, Sham Wat River (Chan, 2001 as Sarotherodon
mossambicus); Tai O River (Ove Arup & Partners Hong
Kong Limited, 2002 as Sarotherodon mossambicus); Sha
Ha Stream, Pak Kong River (Maunsell Consultants Asia
Limited, 2004 as Sarotherodon mossambicus); Sam Dip
Tam Stream, Tso Kung Tam Stream (Mott Connell Limited,
2005 as Sarotherodon mossambicus); Luk Tei Tong River
(Maunsell Consultants Asia Limited, 2005a as Sarotherodon
mossambicus); Lam Tin area (Maunsell Consultants Asia
Limited, 2005b as Sarotherodon mossambicus); Siu Ma
Shan area (Black & Veatch Hong Kong Limited, 2006
as Sarotherodon mossambicus); Nam Long Shan area
(within Ocean Park) (Maunsell Environmental Management
Consultants Limited, 2006 as Sarotherodon mossambicus);
Kam Tin River (Black & Veatch Hong Kong Limited, 2005
as Sarotherodon mossambicus; DSD, 2021; current survey);
Man Uk Pin Stream (Black & Veatch Hong Kong Limited,
2007); Mai Po Nature Reserve (WWF, 2006; WWF, 2021);
Wo Shang Wai area (Mott Connell Limited, 2008); Fung
Lok Wai area (CH2M HILL Hong Kong Limited, 2008);
Tsang Tsui area (Metcalf & Eddy Limited, 2008); Sha Lo
Wan area, Pak Mong area (Ove Arup & Partners Hong Kong
Limited, 2009); Big Wave Bay Stream (DSD, 2010); Hok Tau
Reservoir, Kowloon Reservoir, Pok Fu Lam Reservoir, Shek
Lei Pui Reservoir, Tai Tam Tuk Reservoir (Lai, 2011); Tei
Lung Hau area (Ove Arup & Partners Hong Kong Limited,
2011); Kong Nga Po area (Mott MacDonald Hong Kong
Limited, 2013); Fanling area, Kwu Tung area (Ove Arup &
Partners Hong Kong Limited, 2013b); Cheung Chau Island
(Atkins China Limited, 2013); Tai Sheung Tok area (Ove
Arup & Partners Hong Kong Limited, 2014); Tseng Lan
Shue area (Black & Veatch Hong Kong Limited, 2018);
Nam Sang Wai area (Black & Veatch Hong Kong Limited,
2020a); Nam Wa Po area (DSD, 2020); Nai Chung Stream
(AECOM Asia Company Limited, 2021b); Tai Po Kau
Nature Reserve (AFCD, 2021c); Ma Wat River, Ping Yuen
River, Ngong Ping Stream, Ma Tso Lung Stream, Tong Fuk
River, Ho Chung River, Pak Ngan Heung Stream, Ngau Tam
Mei River, Yuen Long Bypass Floodway, Deep Water Bay
Stream, Ping Kong Stream, Cheung Po Stream, Wong Lung
Hang Stream, Tai Tei Tong Stream, Shek Kong Stream, Sai
Kung River, Fo Tan Nullah, Pui O Stream (DSD, 2021);
Tai Po River, Lions Nature Education Centre, Kwu Tung
Reservoir, Kwun Yam Shan Stream, Kowloon Reception
Reservoir (GBIF.org, 2021); Tung Chung River (Green
Power, 2021); Waterfall Bay Stream, Sha Po area, Lau
Shui Heung Reservoir, Tai Lam Chung Reservoir, Shing
Mun Reservoir, Shap Long Irrigation Reservoir, Kai Tak
River, Kowloon Byewash Reservoir, Kai Tak River; Ting
Kok area (current survey).
Native range. Africa.
Remarks. First imported into Hong Kong as aquarium
specimens during the 1940s, with further imports for the
development of aquaculture in the 1950s (Man, 1974). It
has been released in various reservoirs around Hong Kong
by the local government. It is presently abundant and
widespread in polluted river channels in the New Territories.
However, many localities where Oreochromis mossambicus
was historically recorded (especially reservoirs) are now
dominated by O. niloticus and Coptodon zillii. Oreochromis
mossambicus differs from other members of the genus in
that females and non-breeding males are silver-coloured
with 2–5 mid-lateral black blotches and occasionally black
dorsal bars; breeding males are all black except for a pale
patch on the operculum, and red margins on the dorsal and
caudal ns (Trewavas, 1983).
Oreochromis niloticus (Linnaeus)
(Fig. 35, [LU])
Fig. 35. Oreochromis niloticus, 150.3 mm SL, Kowloon Reservoir.
Distribution. Tai Chung Hau area, Lam Tsuen River, Kau
Lung Hang Lo Wai area, Shuen Wan area, Sha Ling area,
Tan Shan River, Pui O Stream, Tong Fuk River, Tai O River,
Tai Ho River (Chan, 2001); Lung Mei area (Halcrow China
Limited, 2007); Fung Lok Wai area (CH2M HILL Hong Kong
Limited, 2008); Tsang Tsui area (Metcalf & Eddy Limited,
2008); Sha Lo Wan area (Ove Arup & Partners Hong Kong
Limited, 2009); Big Wave Bay Stream (DSD, 2010; current
survey); Kong Nga Po area (Mott MacDonald Hong Kong
Limited, 2013); Fanling area, Kwu Tung area (Ove Arup &
Partners Hong Kong Limited, 2013b); Ho Pui Reservoir, Hok
Tau Reservoir, Shing Mun Reservoir, Kowloon Reservoir,
Plover Cove Reservoir, Pok Fu Lam Reservoir, Kowloon
Reception Reservoir, Shek Lei Pui Reservoir (Lai, 2011;
current survey); Sandy Ridge Cemetery (Ove Arup &
Partners Hong Kong Limited, 2016); Mui Tsz Lam stream
(AECOM Asia Company Limited, 2016a); Hung Shui Kiu
area (AECOM Asia Company Limited, 2016b); Shan Ha
Tsuen area, Muk Kiu Tau Tsuen area, Tai Tong area (Ove
Arup & Partners Hong Kong Limited, 2017); Sung Shan
New Village, Lin Fa Tei area, Ha Che area (Atkins China
Limited, 2020); Yuen Long Town Nullah (Black & Veatch
Hong Kong Limited, 2020a); Hong Po Road area (Black
& Veatch Hong Kong Limited, 2020b); Nam Wa Po area
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RAFFLES BULLETIN OF ZOOLOGY 2023
(DSD, 2020); Shek Kiu Tau area (Mott MacDonald Hong
Kong Limited, 2020); Pak Tin area (Tai Wai) (AECOM
Asia Company Limited, 2021a); Lau Shui Heung Reservoir
(AFCD, 2021c); Ma Wat River, Ping Yuen River, Pak Ngan
Heung Stream, Ma Tso Lung Stream, Ngau Tam Mei River,
Yuen Long Bypass Floodway, Ho Chung River, Kam Tin
River, Ping Kong Stream, Cheung Po Stream, Wong Lung
Hang Stream, Tai Tei Tong Stream, Shek Kong Stream, Ho
Pui River, Deep Water Bay Stream (DSD, 2021); Wetland
Park, Hang Tau area, Tin Shui Wai Park, Tai Po Kau Nature
Reserve, Sheung Yue River, Tin Shui Wai River, She Shan
River, Ting Kok area, Nam Sang Wai area, San Tin area,
Kai Tak River, High Island Reservoir, Hung Shui Hang
Irrigation Reservoir, Shan Pui River (GBIF.org, 2021);
Tung Chung River (Green Power, 2021; current survey);
Mai Po Nature Reserve (WWF, 2021); Kowloon Byewash
Reservoir; Lam Tei Irrigation Reservoir, Tai Shui Hang area,
Aberdeen Lower Reservoir, Aberdeen Upper Reservoir, Tai
Tam Reservoir, Tai Tam Tuk Reservoir, Tai Tam Byewash
Reservoir, Tai Tam Intermediate Reservoir (current survey).
Native range. Africa.
Remarks. The introduction of this species has not been as
well documented as that of O. mossambicus. However, this
species may have been misidentied as O. mossambicus in
earlier studies. Presently, O. niloticus appears to be relatively
abundant and has replaced O. mossambicus in numerous
habitats. It differs from other Oreochromis spp. in that the
caudal n has black bars, and the upper margin of the dorsal
n is black or grey and never entirely fringed with red as in
O. mossambicus, O. aureus, or hybrids (Trewavas, 1983).
Oreochromis mossambicus × O. niloticus hybrid
Distribution. Tung Chung River, Pak Ngan Heung Stream,
Shing Mun Reservoir, Lower Shing Mun Reservoir, Sha
Kok Mei area, Tung Tsz Stream, Pui O Stream, Ting Kok
area, Wang Tong River, Kai Tak River, Wong Lung Hang
Stream, Shan Pui River, Tai O River, Po Toi Island, Lions
Nature Education Centre, Big Wave Bay Stream, Tai Chung
Hau area (H.T. Cheng, pers. comm., 2021); Sheung Yue
River, Ho Chung River, Tai Shui Hang area (current survey).
Remarks. This hybrid is likely more widespread than currently
reported, given that its morphological similarity to both parent
species increases the likelihood of misidentication (Van
der Bank & Deacon, 2007). While genetic analyses are the
most effective mode of verication, hybrids can also be
recognised by breeding males that do not turn completely
black (usually dark grey), and the caudal ns with black
bars and red margins (Tan et al., 2020).
Oreochromis niloticus × O. aureus hybrid
(Fig. 36, [LU])
Fig. 36. Oreochromis niloticus × O. aureus hybrid, 128.8 mm
SL, Pui O Stream.
Distribution. Pui O Stream (current study).
Remarks. A single hybrid (100% DNA match) was collected
from Pui O Stream.
Parachromis managuensis (Günther)
(Fig. 37, [LU])
Fig. 37. Parachromis managuensis, 35.1 mm SL, Plover Cove
Reservoir.
Distribution. Plover Cove Reservoir (GBIF.org, 2021;
current survey).
Native range. Central and South America.
Pelmatolapia mariae (Boulenger)
Distribution. Tai Lam Chung Reservoir (AFCD, 2021c); Pak
Ngan Heung Stream (DSD, 2021); Ting Kok area (GBIF.
org, 2021; current survey).
Native range. Africa.
Vieja bifasciata (Steindachner)
(Fig. 38, [LU])
Fig. 38. Vieja bifasciata, 103.6 mm SL, Tai Tam Tuk Reservoir.
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Chan et al.: Non-native shes of Hong Kong
Distribution. Tai Tam Reservoir, Tai Tam Byewash
Reservoir (GBIF.org, 2021; current survey); Hok Tau
Reservoir; Tai Tam Tuk Reservoir (current survey).
Native range. Central and South America.
Vieja fenestrata (Günther)
(Fig. 39, [LU])
Blood-red Parrot Cichlid
Distribution. Ng Tung River, Kowloon Reservoir, Shing
Mun Reservoir (GBIF.org, 2021).
Remarks. This is a hybrid between Amphilophus citrinellus
× Vieja melanurus, which is popular in the aquarium trade.
Flowerhorn Cichlid
Distribution. Ting Kok area (current survey).
Remarks. Likely a hybrid between Amphilophus labiatus ×
Cichlasoma trimaculatum, which is popular in the aquarium
trade. However, it is possible for other cichlids to be crossed,
which may give rise to various forms.
Order Atheriniformes
Family Melanotaeniidae
Melanotaenia trifasciata (Rendahl)
(Fig. 41)
Fig. 39. Vieja fenestrata, 103.6 mm SL, Hok Tau Reservoir.
Distribution. Pak Ngan Heung Stream, Lam Tsuen River
(DSD, 2021); Plover Cove Reservoir, Ng Tung River, Sheung
Yue River, Aberdeen Lower Reservoir, Kwu Tung Reservoir,
Tan Shan River, Shing Mun Reservoir, Kowloon Reception
Reservoir (GBIF.org, 2021; current survey); Duck Pool
(Kwan Tei North), Yung Shue O Stream, Aberdeen Upper
Reservoir, Tai Lam Chung Reservoir, Pok Fu Lam Reservoir,
Tai Tam Byewash Reservoir, High Island Reservoir (H.T.
Cheng, pers. comm., 2021); Hok Tau Reservoir, Lower
Shing Mun Reservoir (current survey).
Native range. Central and South America.
Vieja melanurus (Günther)
(Fig. 40)
Fig. 40. Vieja melanurus, Lai King area.
Distribution. Plover Cove Reservoir (GBIF.org, 2021);
Lower Shing Mun Reservoir (GBIF.org, 2021); Lai King
area (current survey).
Native range. Central and South America.
Vieja zonata (Meek)
Distribution. Lam Tei Irrigation Reservoir (GBIF.org, 2021);
Hung Shui Hang Irrigation Reservoir, Tin Shui Wai River
(H.T. Cheng, pers. comm., 2021).
Native range. Central and South America.
Fig. 41. Melanotaenia trifasciata, Black Hill.
Distribution. Black Hill area (current survey).
Native range. Australasia.
Remarks. A single individual recorded in a hill stream on
Black Hill is likely a released aquarium specimen as it is
commonly sold in Hong Kong.
Order Cyprinodontiformes
Family Aplocheilidae
Aplocheilus lineatus (Valenciennes)
(Fig. 42, [LU])
Fig. 42. Aplocheilus lineatus, 54.5 mm SL, Deep Water Bay Stream.
Distribution. Deep Water Bay Stream (current survey).
Native range. India and Sri Lanka, South Asia.
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RAFFLES BULLETIN OF ZOOLOGY 2023
Remarks. Found to have a sizable breeding population
in a man-made pond in Deep Water Bay Stream in 2020
to 2021. However, it was not recorded during subsequent
surveys in 2022.
Family Poeciliidae
Gambusia afnis (Baird & Girard)
(Fig. 43, [LU])
Partners Hong Kong Limited, 2014); Muk Kiu Tau Tsuen
area, Nam Hang Pai area, Shan Ha Tsuen area, Lam Hau
Tsuen area, Shap Pat Heung area, Shek Tong Tsuen area
(Ove Arup & Partners Hong Kong Limited, 2017); Tseng
Lan Shue area (Black & Veatch Hong Kong Limited, 2018);
Nam Sang Wai area (Black & Veatch Hong Kong Limited,
2020a; current survey); Nam Wa Po area (DSD, 2020);
Pak Tin area (Tai Wai) (AECOM Asia Company Limited,
2021a); Nai Chung Stream (AECOM Asia Company Limited,
2021b);Tai Po Kau Nature Reserve (AFCD, 2021c); Ma
Wat River, Ping Yuen River, Ngong Ping Stream, Ma Tso
Lung Stream, Tong Fuk River, Ho Chung River, Pak Ngan
Heung Stream, Ngau Tam Mei River, Yuen Long Bypass
Floodway, Deep Water Bay Stream, Ping Kong Stream,
Wong Lung Hang Stream, Tai Tei Tong Stream, Shek Kong
Stream, Sai Kung River, Fo Tan Nullah (DSD, 2021); Tai
Po River, Lions Nature Education Centre, Lamma Island
area, Kwu Tung Reservoir, San Tin area, Kwun Yam Shan
Stream, Kowloon Reception Reservoir (GBIF.org, 2021);
Tung Chung River (Green Power, 2021; current survey);
Little Hawaii Stream, Fung Yuen Stream, Tung Tsz Stream,
Kau Lung Hang Lo Wai Stream, Heung Yuen Wai Stream,
Tsing Tam Tsuen Stream, Yeung Ka Tsuen Stream, So
Kwun Wat Stream (Tsang & Dudgeon, 2021a); Waterfall
Bay Stream, Sha Po area, Lau Shui Heung Reservoir, Tai
Lam Chung Reservoir, Shing Mun Reservoir, Plover Cove
Reservoir, Shap Long Irrigation Reservoir, Hung Shui Hang
Irrigation Reservoir, Lam Tei Irrigation Reservoir, Ho Pui
Reservoir, Kowloon Byewash Reservoir, Kai Tak River,
Aberdeen Lower Reservoir, Aberdeen Upper Reservoir,
Wong Nai Chung Reservoir, Tai Tam Reservoir, Tai Tam
Byewash Reservoir, Tai Tam Intermediate Reservoir, High
Island Reservoir, Wong Nai Tun Irrigation Reservoir, Sham
Tseng Settlement Basin, Shek Pik Reservoir, Yi O Stream,
Kau Ling Chung Stream (current survey).
Native range. Central and North America.
Remarks. The most widespread non-native sh in Hong
Kong, and was released by the Hong Kong Government for
mosquito control around 1940 (Dudgeon & Corlett, 2004).
Poecilia reticulata (Peters)
(Fig. 44, [LU])
Distribution. Lam Tsuen River, Shuen Wan area, Wang
Tong River, Sha Lo Wan Stream, (Chan, 2001); Fung Yuen
area (Mouchel Asia Limited, 2002); Tai Po Tsai area (Allied
Environmental Consultants Limited, 2004); Lam Tin area
(Maunsell Consultants Asia Limited, 2005b); Man Uk Pin
Stream (Black & Veatch Hong Kong Limited, 2007); Lung
Mei area (Halcrow China Limited, 2007); Ping Yuen River
(Ove Arup & Partners Hong Kong Limited, 2007); Fanling
area, Kwu Tung area (Ove Arup & Partners Hong Kong
Limited, 2013b); Cheung Chau Island area (Atkins China
Limited, 2013); Sandy Ridge Cemetery (Ove Arup & Partners
Hong Kong Limited, 2016); Muk Kiu Tau Tsuen area, Tai
Tong area, Shan Ha Tsuen area (Ove Arup & Partners Hong
Kong Limited, 2017); Lai Chi Wo area (So, 2019); Sung
Shan New Village area, Lin Fa Tei area, Ha Che area (Atkins
Fig. 43. Gambusia afnis, 23.9 mm SL female (top), Lam Tsuen
River, 18.2 mm SL male (bottom), Lin Au Stream.
Distribution. Lamma Island area, Luk Tei Tong area, Luk
Keng area, Pui O area, Sham Chung area, Sha Lo Tung area
(Dudgeon & Chan, 1996); Lok Ma Chau area (Environmental
Resources Management Hong Kong Limited, 1999a); Lam
Tei area (Environmental Resources Management Hong Kong
Limited, 1999b); Pun Chun Yuen Stream, Lam Tsuen River
(Mott Connell Limited, 2000); Tai Chung Hau area, Shuen
Wan area, Lin Ma Hang Stream, Sandy Ridge Cemetery,
Sha Ling area, Loi Tung area, Sheung Wo Hang Stream, Tai
Tong area, Cheung Po Stream, Wang Tong River, Sham Wat
Stream (Chan, 2001); Tai O River (Ove Arup & Partners
Hong Kong Limited, 2002); Sha Ha Stream, Pak Kong
River (Maunsell Consultants Asia Limited, 2004); Kam Tin
River (Black & Veatch Hong Kong Limited, 2005; DSD,
2021); Sam Dip Tam Stream, Tso Kung Tam Stream (Mott
Connell Limited, 2005); Luk Tei Tong River (Maunsell
Consultants Asia Limited, 2005a); Lam Tin area (Maunsell
Consultants Asia Limited, 2005b); Siu Ma Shan area (Black
& Veatch Hong Kong Limited, 2006); Nam Long Shan area
(within Ocean Park) (Maunsell Environmental Management
Consultants Limited, 2006); Mai Po Nature Reserve (WWF,
2006; WWF, 2021); Man Uk Pin Stream (Black & Veatch
Hong Kong Limited, 2007); Lung Mei area (Halcrow China
Limited, 2007); Wo Shang Wai area (Mott Connell Limited,
2008); Fung Lok Wai area (CH2M HILL Hong Kong
Limited, 2008); Tsang Tsui area (Metcalf & Eddy Limited,
2008); Sha Lo Wan area, Pak Mong area (Ove Arup &
Partners Hong Kong Limited, 2009); Big Wave Bay Stream
(DSD, 2010); Hok Tau Reservoir, Kowloon Reservoir, Pok
Fu Lam Reservoir, Shek Lei Pui Reservoir, Tai Tam Tuk
Reservoir (Lai, 2011; current survey); Tei Lung Hau area
(Ove Arup & Partners Hong Kong Limited, 2011); Kong
Nga Po area (Mott MacDonald Hong Kong Limited, 2013);
Fanling area, Kwu Tung area (Ove Arup & Partners Hong
Kong Limited, 2013b); Cheung Chau Island area (Atkins
China Limited, 2013); Tai Sheung Tok area (Ove Arup &
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Chan et al.: Non-native shes of Hong Kong
China Limited, 2020); Pak Tin area (Tai Wai), Pok Hong
area, Chun Shek area (AECOM Asia Company Limited,
2021a); Sha Lo Tung Stream, Tai Po Kau Nature Reserve,
Shap Long Irrigation Reservoir (AFCD, 2021c; current
survey); Pak Ngan Heung Stream, Pui O Stream, Wong Lung
Hang Stream, Tai Tei Tong Stream, Ngong Ping Stream,
Shek Kong Stream (DSD, 2021); Lion’s Nature Education
Centre, Mui Tsz Lam Stream, Ha Wo Hang area, Ng Tung
River, Tung Ma To Stream (GBIF.org, 2021); Tung Chung
River (Green Power, 2021; current survey); Little Hawaii
Stream, Tai Tung Wo Liu Stream, Man Hang Stream, Sam
Dip Tam Stream, Tung Tsz Stream, Kau Lung Hang Lo
Wai Stream, Tsing Tam Tsuen Stream, Tsui Keng area, So
Kwun Wat Stream, Pak Long Stream (Tsang & Dudgeon,
2021a); Deep Water Bay Stream (current survey).
Native range. Central and South America.
Remarks. This species was introduced alongside Gambusia
afnis by the Hong Kong Government for mosquito control
around 1940 (Dudgeon & Corlett, 2004). Escapees or
discards from the aquarium trade and individuals released
during Buddhist rituals may have also contributed to their
establishment in many parts of Hong Kong (Tricarico et al.,
2016). However, this species appears to be less widespread
than it was in the 1980s.
Distribution. Tsing Yi area, Sha Tin area (GBIF.org, 2021);
Sha Po area (current survey).
Native range. Central and South America.
Remarks. Common in the aquarium trade.
Poecilia salvatoris (Regan)
(Fig. 46, [LU])
Distribution. Lam Tsuen River (DSD, 2021; current survey);
Sam Dip Tam Stream, Tung Tsz Stream (Tsang & Dudgeon,
2021a; current survey).
Native range. Central and South America.
Remarks. Most abundant in a rocky hillstream (Sam Dip
Tam Stream).
Poecilia sphenops (Valenciennes)
(Fig. 47.)
Fig. 47. Poecilia sphenops (melanistic variety), Lam Tsuen River,
note damaged dorsal n, photographed by Chun Hin Wan.
Distribution. Lam Tsuen River (Chan, 2001; C.H. Wan,
pers. comm., 2021).
Fig. 44. Poecilia reticulata, 24.8 mm SL female (top), 18.1 mm SL
wild-type male (middle), Lin Au Stream, 19 mm SL ornamental
male (bottom), Lohas Park.
Poecilia wingei (Poeser, Kempkes & Isbrücker)
(Fig. 45.)
Fig. 45. Poecilia wingei, Sha Po area.
Fig. 46. Poecilia salvatoris, 30 mm SL female (top), Lam Tsuen
River, 30 mm SL male (bottom), Sam Dip Tam Stream.
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Native range. Central and South America.
Remarks. Has only been recorded twice, twenty years apart.
It is scarce in the wild despite its prevalence in the local
aquarium trade, suggesting that it has difculty establishing
itself.
Xiphophorus hellerii (Heckel)
(Fig. 48, [LU])
Tun Ha Stream, She Shan River, Sam Dip Tam Stream, Kau
Lung Hang Lo Wai Stream, Tan Shan River, Tsing Tam
Tsuen Stream (Tsang & Dudgeon, 2021a); Deep Water Bay
Stream (current survey).
Native range. Central and South America.
Remarks. Pathways of introduction include Buddhist
release rituals and/or discarded pets from the aquarium
trade (Tricarico et al., 2016). Aquarium cultivars (Fig 48,
red-variety), of this species were encountered during the
current study, indicating that they are still being actively
released. This species is more widespread and abundant than
Gambusia afnis in relatively unpolluted lowland streams
(Tsang & Dudgeon, 2021a).
Xiphophorus maculatus (Günther)
Distribution. Wong Lung Hang Stream, Tan Shan River,
Sam Dip Tam Stream, Kau Lung Hang Lo Wai Stream, Fung
Yuen Stream (Tsang & Dudgeon, 2021a); Tai Po Tsai area,
Deep Water Bay area (H.T. Cheng, pers. comm., 2021); Shui
Hau Stream (current survey).
Native range. Central and South America.
Remarks. Breeding populations (wild-type) have been
found only in the Tan Shan River, while other populations
comprised only of freshly released ornamental variants.
These sh are usually sold as live sh food but have also
been sold for use in Buddhist release rituals.
Xiphophorus variatus (Meek)
(Fig. 49, [LU])
Fig. 48. Xiphophorus hellerii, 34.8 mm SL female (top), 35.1 mm
SL male (middle), Wong Lung Hang Stream, 38.8 mm SL red-
variety male (bottom), Tai Po Kau Nature Reserve.
Distribution. Lam Tsuen River (Chan, 2011; current survey)
Shuen Wan area, Wang Tong River, Sha Lo Wan Stream
(Chan, 2001); Fung Yuen area (Mouchel Asia Limited,
2002); Tai Po Tsai area (Allied Environmental Consultants
Limited, 2004); Luk Tei Tong River (Maunsell Consultants
Asia Limited, 2005a); Lung Mei area (Halcrow China
Limited, 2007); Ping Yuen River (Ove Arup & Partners
Hong Kong Limited, 2007); Tei Lung Hau area (Ove Arup
& Partners Hong Kong Limited, 2011); Fanling area (Ove
Arup & Partners Hong Kong Limited, 2013b); Tai O River
(Atkins China Limited, 2016); Lai Chi Wo area (So, 2019);
Sung Shan New Village area, Ha Che area (Atkins China
Limited, 2020); Sha Lo Tung Stream, Tai Po Kau Nature
Reserve, Shap Long Irrigation Reservoir (AFCD, 2021c;
current study); Pak Ngan Heung Stream, Pui O Stream,
Wong Lung Hang Stream, Tai Tei Tong Stream, Ngong
Ping Stream, Shek Kong Stream (DSD, 2021); Lion’s Nature
Education Centre, Tung Tsz Stream, Mui Tsz Lam Stream,
Ha Wo Hang area, Ng Tung River, Tung Ma To Stream
(GBIF.org, 2021); Tung Chung River (Green Power, 2021;
current survey); Little Hawaii Stream, Ho Chung River, Tai
Chung Hau Stream, Tai Mong Tsai Stream, Hoi Ha Stream,
Tai Tung Wo Liu Stream, Pak Tin area (Tai Wai), Yuen
Fig. 49. Xiphophorus variatus, 37.2 mm SL female (top),
27.7 mm SL male (bottom), Wong Lung Hang Stream.
Distribution. Ho Chung River, Hoi Ha Stream, Shap Sze
Heung area, Lam Tsuen River, Kau Lung Hang Lo Wai
Stream, Wang Tong River (Chan, 2001); Sha Ha Stream
(Maunsell Consultants Asia Limited, 2004); Sam Dip Tam
Stream, Tso Kung Tam Stream (Mott Connell Limited,
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Chan et al.: Non-native shes of Hong Kong
2005); Lung Mei area (Halcrow China Limited, 2007); Big
Wave Bay Stream (DSD, 2010); Tai Tam Tuk Reservoir
(Lai, 2011); Pok Fu Lam Reservoir (Lai, 2011; GBIF.org,
2021); Tei Lung Hau area (Ove Arup & Partners Hong Kong
Limited, 2011); Tai Sheung Tok area (Ove Arup & Partners
Hong Kong Limited, 2014); Mui Tsz Lam stream (AECOM
Asia Company Limited, 2016a; current survey); Hung Shui
Kiu area (AECOM Asia Company Limited, 2016b); Tai O
River (Atkins China Limited, 2016; current survey); Tseng
Lan Shue area (Black & Veatch Hong Kong Limited, 2018);
Ha Che area (Atkins China Limited, 2020); Pak Tin area
(Tai Wai) (AECOM Asia Company Limited, 2021a); Sha
Lo Tung Stream (AFCD, 2021c); Sai Kung River, Wong
Lung Hang Stream, Pak Ngan Heung Stream, Tai Tei Tong
Stream, Cheung Po Stream, Shek Kong Stream (DSD, 2021);
Fung Yuen area, Chuen Lung area, Sha Kok Mei area, Pui
O Stream, Tung Ma To Stream (GBIF.org, 2021); Tung
Chung River (Green Power, 2021; current survey); Little
Hawaii Stream, Tai Chung Hau Stream, Hoi Ha Stream,
Tai Lung Wo Liu Stream, Yuen Tun Ha Stream, She Shan
River, Tung Tsz Stream, Tan Shan River, Tsing Tam Tsuen
Stream (Tsang & Dudgeon, 2021a); Tong Fuk River, Deep
Water Bay Stream (current survey).
Native range. Central and South America.
Remarks. Often coexists with Xiphophorus hellerii in Hong
Kong streams.
Order Beloniformes
Family Hemiramphidae
Hyporhamphus intermedius (Cantor)
(Fig. 50, [LU])
Xenentodon cancila (Hamilton)
Distribution. Kowloon Reservoir (Lai, 2011; GBIF.org,
2021); Kowloon Byewash Reservoir (GBIF.org, 2021).
Native range. South Asia.
Order Centrarchiformes
Family Centrarchidae
Micropterus salmoides (Lacepède)
(Fig. 51, [LU])
Fig. 50. Hyporhamphus intermedius, 118.2 mm SL, Tai Lam
Chung Reservoir.
Distribution. Plover Cove Reservoir; Tai Lam Chung
Reservoir (current survey).
Native range. Northwest Pacic, including South China
(East Asia).
Remarks. Individuals DNA sequenced from both localities
revealed a 4.1% divergence from Hyporhamphus intermedius,
indicating it could be a different species despite morphological
similarities. Integrative taxonomic work and genetic sampling
from this genus is necessary for further verication.
Fig. 50. Micropterus salmoides, Lam Tei Irrigation Reservoir.
Distribution. Tai Tam Reservoir (Man & Hodgkiss, 1981);
Ho Pui Reservoir (Lai, 2011); Hok Tau Reservoir (Lai, 2011;
AFCD, 2021c); Lau Shui Heung Reservoir (AFCD, 2021c);
Hung Shui Hang Irrigation Reservoir, Lam Tei Irrigation
Reservoir; Kwu Tung Reservoir, Tai Tam Intermediate
Reservoir, Plover Cove Reservoir (GBIF.org, 2021; current
survey); Shing Mun Reservoir (current survey).
Native range. North America.
Remarks. First released into some local reservoirs for
angling purposes around 1935 (Law, 2006) and still has
breeding populations.
DISCUSSION
Composition of non-native freshwater shes in Hong
Kong. A total of 95 non-native freshwater fishes (and
ve putative hybrids) were recorded, half of which were
associated with breeding populations. Cichlidae, Cyprinidae,
Poecilidae, and Xenocyprididae were the most speciose
families, resembling reports from mainland China (Xiong
et al., 2015) and Singapore (Tan et al., 2020). Cichlids
and cyprinids were similarly dominant in the Philippines
(Cagauan, 2007). Most non-native fishes entered Hong
Kong via the aquarium trade (64 species) or aquaculture (23
species). This is again similar to ndings from the Philippines
(Cagauan, 2007), mainland China (Xiong et al., 2015) and
Singapore (Tan et al., 2020), as well as the United States
(Nico & Fuller, 1999).
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With the exception of ve putative hybrids, the non-native
shes originated from: Central or South America (27 species),
East Asia (21 species), Southeast Asia (15 species), Africa
(15 species), South Asia (10 species), North America (ve
species), Australasia (one species), and Europe (one species).
In addition, the majority of non-native sh in Hong Kong
(70%) were from tropical regions, which is lower than in
Singapore (82.9%; Tan et al., 2020), but is a likely reection
of the warm climate in both locations.
Introductions over time. The number of non-native
fish species has risen dramatically in the past 30 years
(Fig. 47), with a ve-fold increase in the number of non-
native species since the previous annotated compilation
of freshwater fishes by Chong & Dudgeon (1992). Our
results show that non-native freshwater fishes in Hong
Kong were introduced mainly through the aquarium trade
(64 species), followed by aquaculture (23 species), and
water transfer from the Dongjiang in mainland China (13
species). Species introductions from the aquarium trade
and aquaculture reect an increasing trend since the 1990s
(Fig. 52), possibly because both industries are increasingly
reliant on imported shes (FHB, 2011; Ho, 2013), given
the declining protability in breeding aquarium/aquaculture
species locally. Similarly, increases in species introductions
from the Dongjiang mirrors the rising importance of water
imports that represent 60-80% of annual supply in 1989-
2015 compared to only 20% in the 1960s (ADMCF, 2017).
This increase in the volume of imported water increases the
likelihood of species establishment (Table 2) as propagule
pressure is greater (Simberloff, 2009).
Aquarium trade. Sixty-two non-native species traded as
aquarium shes in Hong Kong were recorded in local fresh
waters, of which 27 species originated from Central and
Fig. 52. First records of non-native freshwater sh species from 1930 to 2022 and their suspected introduction sources.
Table 2. Freshwater sh species suspected to be introduced into
Hong Kong through water transfers from mainland China.
Family Species
ENGRAULIDAE Coilia grayii
CYPRINIDAE Parabramis pekinensis
XENOCYPRIDIDAE Chanodichthys erythropterus
Culter recurviceps
Hemiculter bleekeri
Opsariichthys sp.
Toxabramis houdemeri
GOBIONIDAE Sarcocheilichthys nigripinnis
BAGRIDAE Tachysurus vachellii
Tachysurus fulvidraco
Tachysurus virgatus
HEMIRAMPHIDAE Hyporhamphus intermedius
South America, 11 from Southeast Asia, 10 from Africa, six
from South Asia, ve from North America, two from East
Asia, and one from Australasia. In total, 27 of them were
associated with breeding populations, indicating that more
than 40% of species introduced by way of the aquarium trade
have become established in Hong Kong. Propagule pressure
from the aquarium trade may have increased over time due
to the diversication of introduction pathways. In the past,
non-native shes in aquaria were introduced as escapees
from sh farms, mosquito control agents (only Poeciliids),
and for angling purposes (Lin, 1949; Dudgeon & Corlett,
2004). At present, sh releases during Buddhist rituals or
as unwanted pets are commonplace.
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A study on the invasion risk of ornamental freshwater sh
in Hong Kong by Ho (2013) using the Fish Invasiveness
Screening Kit (FISK) indicated that Carassius auratus
(FISK score 31), Cyprinus carpio (FISK score 26.5),
Pterygoplichthys anisitsi (FISK score 26), P. gibbiceps
(FISK score 25), Xiphophorus hellerii (FISK score 18),
and Silurus glanis (FISK score 18), had a high chance of
becoming invasive in Hong Kong (Ho, 2013). Of these, C.
auratus, C. carpio, and X. hellerii are locally widespread,
although the former two may also have native populations.
While P. anisiti and P. gibbiceps have not been recorded
in the wild, it is possible that they have been misidentied,
owing to difculties in differentiating between members of
the loricariid genus Pterygoplichthys currently in Hong Kong
and South China (Wei et al., 2017). This is a potential cause
for concern as only 25 species traded through Hong Kong
were selected randomly for the study’s FISK assessment
(of which 20% were found to be high risk), although other
species may be equally, or even more invasive (e.g., Poecilia
reticulata and Hemichromis gutattus).
Hotspots. Non-native sh species were reported throughout
Hong Kong (Fig. 53), with the highest frequencies of
occurrence in waterbodies outside of country parks and
reservoirs. Country parks were designated in 1977 to
protect water catchments. This may have contributed to the
preservation of native assemblages in hillstreams above 100
m elevation, as they were relatively insulated from Hong
Kong’s pollution problem during the late 20th century (Binnie
& Partners, 1974; Dudgeon, 1996). Conversely, freshwater
habitats outside of country parks are mostly low elevation
areas that were subject to higher intensity of pollution, habitat
degradation, and alteration (Dudgeon, 1996), with mostly
compromised native communities, which may have allowed
non-native species to establish. Pollutants from farms and
tanneries, in particular, are believed to have driven several
native fishes (e.g., the white cloud mountain minnow,
Tanichthys albonubes) to the point of extirpation in lowland
(unprotected) streams (Weitzman & Chan, 1966). After the
cessation of tannery operations, and restrictions on livestock
raising arising from concerns over zoonoses, local streams
are now in post-pollution recovery but are yet to reach a
state of equilibrium (Tsang & Dudgeon, 2021a). This means
that there may be vacant ecological niches in local streams
that can be exploited by non-native species (Olden et al.,
2006). Moreover, species that become established outside
of their native ranges tend to be tolerant of higher levels of
habitat degradation and pollution (Karatayev et al., 2009).
Reservoirs, on the other hand, represent a novel freshwater
habitat in Hong Kong given the lack of natural lakes or large
rivers. In the absence of native species that have evolved
in similar environments, Hong Kong’s reservoirs are likely
to be susceptible to being quickly overtaken by non-native
shes from various sources discussed earlier (Liew et al.,
2016; Liew et al., 2018).
Ecological impacts. Nearly half (43.4%) of all species-
specic location records were dominated by six species:
Gambusia afnis (119 localities), Oreochromis mossambicus
(89 localities), Oreochromis niloticus (81 localities),
Coptodon zillii (50 localities), Poecilia reticulata (50
localities), and Xiphophorus hellerii (45 localities) (Fig.
54). Of these, we only know about the potential ecological
impacts of poeciliids (i.e., G. afnis, P. reticulata, X. helleri,
X. salvatoris, X. variatus) (Tsang & Dudgeon, 2021a; 2021b;
2021c; 2021d).
The most widespread species, G. affinis, can lower the
abundance and richness of aquatic invertebrates, although
the native Barbodes fasciolatus may have similar effects
(Tsang & Dudgeon, 2021b). However, G. afnis drove greater
reductions in the abundance of wetland invertebrates in the
United States (e.g., over 70% in Missouri and California;
Shulse et al., 2013; Preston et al., 2017) than in Hong Kong
(40%; Tsang & Dudgeon, 2021c). Locally, predation by G.
afnis also reduced the survival of tadpoles from four native
amphibian species (Karraker et al., 2010). Moreover, it has
also been implicated in the decline of the native Oryzias
curvinotus through competition with adults and predation
on eggs and juveniles, as the latter is known only from a
few locations where G. afnis does not occur (Chong &
Dudgeon, 1992).
In general, P. reticulata had weaker effects on aquatic
invertebrates in mesocosms compared to G. affinis,
particularly during the cool dry season (Tsang & Dudgeon,
2021b). This may be because the former has a higher
mean critical thermal minimum (CTmin of P. reticulata:
12.4°C–14.6°C; G. afnis: 5°C–10°C) (Pyke, 2005; Jourdan
et al., 2014). There are limited data on the effects of other
poeciliids in Hong Kong. However, X. hellerii and X.
salvatoris were found to have higher feeding rates than G.
afnis, P. reticulata, and three native sh species in laboratory
settings, suggesting that the two Xiphophorus species may
have greater ecological impacts on native prey (Tsang &
Dudgeon, 2021d). While this is worrying, P. reticulata,
X. helleri, and X. variatus in lowland streams are mainly
herbivorous (Tsang & Dudgeon, 2021a). We nevertheless
believe that these species should be closely monitored,
as X. helleri are known to alter invertebrate communities
and reduce of native sh abundance in invaded streams
(Courtenay & Meffe, 1989; Holitzki et al., 2013).
Cichlidae is the most widespread family of non-native shes
in Hong Kong. While members of this family often impact
local biodiversity (Canonico et al., 2005; Martin et al., 2010),
we lack comprehensive knowledge about potential ecological
impacts in Hong Kong. Dudgeon (1983) reported that O.
mossambicus consumed terrestrial macrophytes in the Plover
Cove Reservoir, while O. niloticus and Coptodon zilli are the
most widespread cichlids in river systems near Hong Kong
(i.e., Guangdong Province; Gu et al., 2019). Cichlids (i.e.,
O. niloticus) in Guangdong Province have been known to
reduce the growth rate of native Cirrhina molitorella, and
may lower the biomass of native shes when occurring in
high abundances (Gu et al., 2015).
Tsang and Dudgeon (2021a) suggested that the ecological
impacts of non-native poeciliids on native sh assemblages
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Fig. 53. Distribution of non-native freshwater sh species in Hong Kong. Each record was location and species-specic, which means
that multiple records of one species in the same locality were represented only once in the heatmap. In total there are 999 locality records
for 93 species (two species have unknown distribution) and ve hybrids.
may be difcult to detect as a consequence of the legacy
effects of pollution in Hong Kong streams. Specically,
non-native species may avoid competing with extant natives
by occupying vacant niches (Cornell, 1999) resulting from
historical pollution-driven extirpations. This phenomenon is
not unprecedented. For instance, non-native round gobies
occupying an empty ecological niche created by an articial
rip-rap have been shown to interact minimally with juvenile
native sh that were relatively unimpacted (Janáč et al.,
2016). This may not be true for other widespread families
of non-native shes, however. As such, we recommend
prioritising the threat assessment of widespread species
(e.g., Fig. 54), especially those that co-occur with locally
threatened natives including Acrossocheilus parallens and
Rhodeus ocellatus (Tsang & Dudgeon, 2021a).
Native shes and hybridisation. Hong Kong has 65 extant
native inland freshwater fish species (Table 3), with at
least ve locally extinct species: Aphyocypris lini; Garra
orientalis; Osteochilus salsburyi; Tanichthys albonubes; and
Cobitis sinensis (Chong & Dudgeon, 1992; AFCD, 2021a).
Based on the findings of the current study, Misgurnus
anguillicaudatus and Channa maculata may hybridise with
non-native congeneric species (M. dabryanus and C. argus
respectively). While, the scale and effects of hybridisation
in Hong Kong are unclear due to a lack of genetic studies,
low rates of introgression were found in natural hybrids of
M. anguillicaudatus × M. dabryanus in mainland China
(You et al., 2009), while C. maculata × C. argus hybrids
crossed in aquaculture had signicantly higher growth rates
than their parent species (Ou et al., 2018), although the
ecological impacts of both hybrids are not well understood.
Non-native fishes from South China. A total of 13
non-native species from South China have been recorded
in Hong Kong: Coilia grayii, Misgurnus dabryanus,
Carassius auratus, Cirrhinus molitorella, Decorus decorus,
Mylopharyngodon piceus, Culter recurviceps, Hemiculter
bleekeri, Sarcocheilichthys nigripinnis, Eugnathogobius
siamensis, Channa argus, Channa striata, and Hyporhamphus
intermedius. The majority of them originate in large
rivers, such as the Dongjiang, so they have been most
frequently found in reservoirs or channelised rivers in the
New Territories, with the exception of M. piceus and D.
decorus (with an unknown distribution and stocked in ponds
respectively). Given the scarcity of knowledge on species
assemblages before the 1940s (Lin, 1949), it is conceivable
that some of these southern Chinese species had native
populations in Hong Kong that had already been extirpated
before ichthyological surveys and recording began.
Management implications. The most effective means of
non-native species management is mitigating ongoing arrival
of propagules (Ruiz & Carlton, 2003) rather than removing
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Chan et al.: Non-native shes of Hong Kong
Fig. 54. Distribution of the six most widespread non-native freshwater sh species in Hong Kong.
species once they have established (Simberloff, 2009). This
is especially critical to Hong Kong’s lowland habitats and
unprotected areas, which are dominated by non-native shes
that may hinder re-colonisation by native shes (Tsang,
2020). Current regulations prohibit the release of animals
into reservoirs (Cap. 102) and public parks (Cap. 132BC),
but other freshwater bodies remain vulnerable to species
introduction. Moreover, species with a history of invasion
can still be imported and sold in Hong Kong. These avenues
for improved legislation and regulatory efforts may provide
achievable options for mitigating and or preventing ecological
impacts (Gozlan et al., 2010; Simberloff et al., 2013).
Lesser-understood sources and pathways, such as water
transfers and Buddhist ritual releases, require more nuanced
approaches and further research due to their societal and
sociological implications. In habitats where non-native
shes have become established, direct eradication through
removal of shes using traps or piscicide (rotenone) has been
suggested to be an effective method (Cano-Rocabayera et
al., 2019). However, trapping can be costly, labour-intensive,
and time-consuming for purposes of complete eradication
when applied without other forms of management (Francis,
2012); for instance, attempts to eradicate Gambusia holbrooki
in a Spanish stream required high-intensity hand-netting
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Table 3. An updated list of native inland freshwater shes in Hong Kong (Chong & Dudgeon, 1992; AFCD, 2022).
Family Species Family Species
MEGALOPIDAE Megalops cyprinoides GOBIIDAE Awaous melanocephalus
ANGUILLIDAE Anguilla japonica Gobiopterus cf. macrolepis
Anguilla marmorata Mugilogobius abei
COBITIDAE Misgurnus anguillicaudatus Mugilogobius chulae
GASTROMYZONTIDAE Liniparhomaloptera disparis Mugilogobius myxodermus
Pseudogastromyzon myersi Redigobius cf. bikolanus
NEMACHEILIDAE Oreonectes platycephalus Rhinogobius duospilus
Schistura fasciolata Rhinogobius leavelli
Schistura incerta Rhinogobius similis
CYPRINIDAE Acrossocheilus beijiangensis Sicyopterus longilis
Acrossocheilus parallens Stiphodon atropurpureus
Barbodes semifasciolatus Stiphodon imperiorientis
DANIONIDAE Rasbora steineri Stiphodon multisquamus
XENOCYPRIDIDAE Aphyocypris normalis Stiphodon palawanensis
Hemiculter leucisculus Stiphodon percnopterygionus
Metzia formosae Tridentiger trigonocephalus
Metzia lineata Glossogobius giuris
Opsariichthys sp. Glossogobius olivaceus
Parazacco spilurus MASTACEMBELIDAE Mastacembelus armatus
ACHEILOGNATHIDAE Rhodeus ocellatus SYNBRANCHIDAE Monopterus albus
GOBIONIDAE Pseudorasbora parva OSPHRONEMIDAE Macropodus hongkongensis
BAGRIDAE Tachysurus trilineatus Macropodus opercularis
SISORIDAE Glyptothorax pallozonus CHANNIDAE Channa asiatica
SILURIDAE Pterocryptis anomala Channa maculata
Silurus asotus ADRIANICHTHYIDAE Oryzias curvinotus
CLARIIDAE Clarias fuscus MUGILIDAE Mugil cephalus
PLECOGLOSSIDAE Plecoglossus altivelis Planiliza subviridis
RHYACICHTHYIDAE Rhyacichthys aspro LUTJANIDAE Lutjanus argentimaculatus
ELEOTRIDAE Eleotris acanthopoma KUHLIIDAE Kuhlia marginata
Eleotris oxycephala Kuhlia rupestris
Giuris tolsoni LATEOLABRACIDAE Lateolabrax maculatus
Hypseleotris cyprinoides TETRAODONTIDAE Takifugu ocellatus
Butis humeralis
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Chan et al.: Non-native shes of Hong Kong
and trapping over three years (Ruiz-Navarro et al., 2013).
Furthermore, regardless of their effectiveness against non-
native shes, piscicides such as rotenone can be detrimental
to native shes and invertebrates (Schreier et al., 2008;
Beaulieu et al., 2021).
This study provides baseline information on the diversity,
distribution, and sources of non-native fishes in Hong
Kong. With 95 species and ve putative hybrids recorded
to date, there are clear signs that non-native fishes are
widespread and well-established, demanding further action.
We recommend investigation of introduction pathways and
potential impacts on vulnerable natives using this paper as
a basis for prioritising non-native species that may warrant
greater concern.
ACKNOWLEDGEMENTS
We would like to thank Alex Lau, Chiu Yui Hong, Samuel
C.L. Ho, Yip Hon Tim, Cai Wenhui for assistance with
eld work; Cheng Hung Tsun, Andrans C. Lam, Wan Chun
Hin and Tse Chung Yi for providing further information on
the distribution of sh and clarications on their iNaturalist
observations; Ken K.Y. So, for providing helpful comments
to the initial manuscript. This study was supported, in part,
by the Lantau Conservation Fund (Grant number: LCF-
RE-2021-02), Lam Woo Research Fund (Grant number:
LWP-20003), and Environment and Conservation Fund (ECF
Project 51/2020). THH would like to thank the Lee Kong
Chian Natural History Museum and the National University
of Singapore for funding his research work.
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APPENDIX
Appendix 1. Names and coordinates of sites sampled during the current study.
Site Coordinates Site Coordinates
Aberdeen Lower Reservoir 22.253322, 114.161966 Sha Lo Tung Stream 22.480089, 114.183792
Aberdeen Upper Reservoir 22.25789, 114.165547 Sha Lo Wan Stream 22.288499, 113.90183
Big Wave Bay Stream 22.246528, 114.245802 Sha Po area 22.452279, 114.051379
Black Hill area 22.304039, 114.244963 Sham Chung area 22.443183, 114.287419
Cheung Chau area 22.202774, 114.023513 Sham Tseng Settlement Basin 22.371024, 114.052793
Cheung Po Stream 22.415439, 114.073976 Sham Wat River 22.266087, 113.888395
Deep Water Bay Stream 22.247207, 114.187269 Shan Pui River 22.454227, 114.030303
Fanling area 22.490255, 114.146584 Shap Long Irrigation Reservoir 22.232474, 113.998911
Fung Yuen Stream 22.466975, 114.179297 Shap Sze Heung area 22.418776, 114.261236
Ha Wo Hang area 22.529698, 114.19875 She Shan River 22.453519, 114.145269
Heung Yuen Wai Stream 22.555504, 114.165461 Shek Kong Stream 22.426685, 114.106617
High Island Reservoir 22.37518, 114.352708 Shek Lei Pui Reservoir 22.355522, 114.14838
Ho Chung River 22.354789, 114.246805 Shek Pik Reservoir 22.231711, 113.898337
Ho Pui Reservoir 22.406282, 114.074923 Sheung Wo Hang Stream 22.523893, 114.194596
Ho Pui River 22.417771, 114.06875 Sheung Yue River 22.511215, 114.111907
Hoi Ha Stream 22.45812, 114.324855 Shing Mun Reservoir 22.385022, 114.147117
Hok Tau Reservoir 22.491702, 114.181359 Shing Mun River 22.384348, 114.196907
Hung Shui Hang Irrigation Reservoir 22.412933, 113.998028 Shuen Wan area 22.500098, 114.240325
Kai Tak River 22.334993, 114.1939 Shui Chuen O Stream 22.371503, 114.196109
Kam Tin River 22.460382, 114.045832 Shui Hau Stream 22.219647, 113.915152
Kau Ling Chung Stream 22.204964, 113.864076 Shui Lo Cho Stream 22.231859, 113.854204
Kau Lung Hang Lo Wai Stream 22.480966, 114.158463 So Kwun Wat Stream 22.376414, 114.008767
Kowloon Byewash Reservoir 22.35028, 114.15068 Tai Chung Hau Stream 22.37317, 114.257404
Kowloon Reception Reservoir 22.350895, 114.145444 Tai Ho River 22.291586, 113.977861
Kowloon Reservoir 22.354392, 114.15522 Tai Lam Chung Reservoir 22.381671, 114.026803
Kwu Tung Reservoir 22.497373, 114.096516 Tai Lung Wo Liu Stream 22.4193, 114.2616
Lai Chi Chong area 22.452089, 114.300826 Tai Mei Tuk area 22.473461, 114.234625
Lai Chi Wo area 22.52572, 114.258824 Tai Mong Tsai Stream 22.392632, 114.299185
Lai King area 22.352973, 114.131668 Tai O River 22.248849, 113.870768
Lam Tei Irrigation Reservoir 22.410179, 113.990084 Tai Po Kau Nature Reserve 22.427919, 114.180707
Lam Tsuen River 22.462016, 114.145906 Tai Po River 22.437604, 114.164404
Lamma Island area 22.214399, 114.133875 Tai Shui Hang area 22.406435, 114.223213
Lau Shui Heung Reservoir 22.496145, 114.168602 Tai Tam Byewash Reservoir 22.25612, 114.211357
Lin Ma Hang Stream 22.550138, 114.18112 Tai Tam Intermediate Reservoir 22.246408, 114.210273
Little Hawaii Stream 22.329063, 114.250074 Tai Tam Reservoir 22.259198, 114.210137
Lohas Park Stream 22.298664, 114.274156 Tai Tam Tuk Reservoir 22.245209, 114.219216
Lok Ma Chau area 22.512653, 114.077514 Tai Tei Tong Stream 22.266916, 113.989179
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Site Coordinates Site Coordinates
Long Valley 22.508498, 114.112873 Tai Tong area 22.420122, 114.020509
Lower Shing Mun Reservoir 22.37265, 114.160156 Tai Tung Wo Liu Stream 22.420803, 114.262039
Lung Mei area 22.472595, 114.225824 Tan Shan River 22.50686, 114.178523
Ma Dai Stream 22.407196, 114.225082 Tin Shui Wai River 22.452648, 113.997787
Ma Wat River 22.490276, 114.146558 Ting Kok area 22.472037, 114.221511
Man Hang Stream 22.401612, 114.189804 Tong Fuk River 22.226842, 113.93094
Man Kam To area 22.526459, 114.123081 Tsing Tai Stream 22.418423, 113.938433
Miu Shan Stream 22.503345, 114.266779 Tsing Tam Reservoir 22.416617, 114.087126
Mui Tsz Lam Stream 22.401794, 114.22669 Tsing Tam Tsuen Stream 22.42033, 114.081027
Mui Wo River 22.264577, 113.993878 Tsing Yi area 22.351894, 114.097221
Nam Sang Wai 22.458117, 114.034447 Tsui Keng area 22.479359, 114.106398
Ng Tung River 22.506301, 114.139241 Tung Chung River 22.276705, 113.929556
Ngong Ping Stream 22.257131, 113.902091 Tung Tsz Stream 22.473185, 114.198595
Pak Long Stream 22.3911, 113.9231 Wang Tong River 22.272261, 113.996408
Pak Ngau Shek Stream 22.443536, 114.125523 Waterfall Bay Stream 22.252829, 114.13365
Pak Tam Chung Stream 22.400432, 114.322524 Wetland Park 22.468978, 114.006808
Pak Tin area (Tai Wai) 22.3823, 114.17332 Wo Shang Wai area 22.487068, 114.052276
Ping Kong Stream 22.489778, 114.123683 Wong Lung Hang Stream 22.276656, 113.943454
Plover Cove Reservoir 22.476641, 114.25637 Wong Nai Chung Reservoir 22.256629, 114.195197
Pok Fu Lam Reservoir 22.265317, 114.137704 Wong Nai Tun Irrigation Reservoir 22.399754, 114.017612
Pui O Stream 22.24389, 113.980547 Wu Kau Tang Stream 22.505706, 114.243558
Sai Kung River 22.388401, 114.270825 Yeung Ka Tsuen Stream 22.412253, 114.020578
Sam Dip Tam Stream 22.38064, 114.12429 Yi O Stream 22.227454, 113.847763
San Tau Stream 22.288688, 113.921646 Yuen Long Bypass Floodway 22.449501, 114.043349
San Tin area 22.495814, 114.072531 Yuen Long Town Nullah 22.44144, 114.025743
Sandy Ridge Cemetery 22.524561, 114.116907 Yuen Tun Ha Stream 22.429276, 114.161213
Sha Ling area 22.533585, 114.127443 Yung Shue O Stream 22.426056, 114.292886
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SUPPLEMENTARY MATERIAL
Supplementary 1. Native species with non-native genetic stock
Table 1. Native freshwater shes with feral populations in Hong Kong (nine species). Region of origin is based on FishBase
(Froese & Pauly, 2021), while introduction pathways have been deduced from ad-hoc surveys, literature, or expert opinions.
Order and Family Species Region of Origin Introduction Pathway Remarks
ORDER CYPRINIFORMES
Family Cobitidae Misgurnus anguillicaudatus East Asia Aquarium trade Established
Family Cyprinidae Garra orientalis East Asia Water transfers Established
Osteochilus salsburyi South Asia Water transfers Established
Family Xenocyprididae Hemiculter leucisculus East Asia Water transfers Established
Family Tanichthyidae Tanichthys albonubes East Asia Aquarium trade Introduced
ORDER GOBIIFORMES
Family Gobiidae Glossogobius olivaceus East Asia Water transfers Established
Gobiopterus cf. macrolepis East Asia Water transfers Established
Mugilogobius myxodermus East Asia Water transfers Established
ORDER ANABANTIFORMES
Family Channidae Channa maculata East Asia Aquaculture Established
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Chan et al.: Non-native shes of Hong Kong
COMPILATION OF NATIVE FRESHWATER FISHES WITH FERAL POPULATIONS
Order Cypriniformes
Family Cobitidae
Misgurnus anguillicaudatus (Cantor)
Distribution. Ho Chung River, Shing Mun Reservoir
(current survey).
Native range. Russia, Korea, Japan, China and Vietnam
(East Asia).
Remarks. This species is occasionally sold as live sh
food along with Paramisgurnus dabryanus in the aquarium
trade, and these shes are often purchased for release in
Buddhist rituals.
Family Cyprinidae
Garra orientalis (Nichols)
Distribution. Tai Lam Chung Reservoir, Plover Cove
Reservoir (A.C. Lam, pers. comm., 2021).
Native range. Asia (presumably East Asia).
Remarks. Native riverine populations of this species have
not been recorded again since Chan (2001) and are suspected
to be extirpated as their local habitat has been channelised. It
is unlikely this species naturally occurred in feeder streams
of the two reservoirs as it usually inhabits tributaries of
large rivers (Pan et al., 1991), which are not present within
the catchments of Tai Lam Chung and Plover Cove. The
populations in the two reservoirs likely arrived through water
transfer from mainland China since this species naturally
occurs in the Dongjiang river system (Guangdong and
Beijiang rivers) (Pan et al., 1991).
Osteochilus salsburyi (Nichols & Pope)
(Fig. 55, [LU])
Fig. 56. Hemiculter leucisculus, 120.2 mm SL, Tai Lam Chung
Reservoir.
Fig. 55. Osteochilus salsburyi, 109 mm SL, Lower Aberdeen
Reservoir.
Distribution. High Island Reservoir, Hok Tau Reservoir,
Shing Mun Reservoir, Lau Shui Heung Reservoir, Plover
Cove Reservoir, Kowloon Reservoir, Shek Lei Pui Reservoir,
Tai Lam Chung Reservoir, Tai Tam Tuk Reservoir (Lai,
2011; current survey); Shek Pik Reservoir (AFCD, 2021c;
current survey); Tai Tam Byewash Reservoir (GBIF.org,
2021; current survey).
Native range. North and South Korea, China, and Japan
(East Asia).
Remarks. This species is suspected to have both native
and non-native populations in Hong Kong (Chong &
Dudgeon, 1992). Reservoir populations are likely to have
been introduced by water transfers from mainland China
and from local rivers.
Distribution. Plover Cove Reservoir (Man & Hodgkiss,
1981; Lai, 2011); Tai Lam Chung Reservoir (Lai, 2011;
current study); High Island Reservoir (Lai, 2011; H.T. Cheng,
pers. comm., 2021); Shing Mun Reservoir (current survey);
Lower Aberdeen Reservoir, Lower Shing Mun Reservoir
(GBIF.org, 2021).
Native range. Laos, Vietnam, and South China (South Asia).
Remarks. Native populations have been historically recorded
in the hill streams of Kam Tin (Lin, 1949), but have not been
recorded in any such streams since except for those owing
directly into reservoirs. This species is often sold as food in
wet markets and releases into reservoirs has been observed.
Family Xenocyprididae
Hemiculter leucisculus (Basilewsky)
(Fig. 56, [LU])
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Family Tanichthyidae
Tanichthys albonubes (Lin)
(Fig. 57.)
Distribution. Tai Po Kau Nature Reserve (current survey).
Native range. China and Vietnam (East Asia).
Remarks. This species once had native populations but was
extirpated during the 1960s (Chong & Dudgeon, 1992). The
individuals observed in the stream at Tai Po Kau Nature
Reserve in 2018 do not resemble those of the wild types
that have been found in Hainan Island and Guangdong
(Chan & Chen, 2009; Zhao et al., 2018), and instead, are
identical to those from the aquarium trade. No individuals
were observed during surveys in Tai Po Kau Nature Reserve
before or after 2018.
Order Gobiiformes
Family Gobiidae
Glossogobius olivaceus (Temminck & Schlegel)
(Fig. 58, [LU])
Fig. 59. Gobiopterus cf. macrolepis, non-native specimen (top),
Tai Lam Chung Reservoir, native specimen (female with eggs)
(bottom), Kam Tin River.
Gobiopterus cf. macrolepis (Cheng)
(Fig. 59, [LU])
Fig. 57. Tanichthys albonubes, 29.5 mm SL, trade material.
Fig. 58. Glossogobius olivaceus, 65 mm SL, Plover Cove Reservoir.
Distribution. Plover Cove Reservoir (Lai, 2011; GBIF.org,
2021; current survey); Tai Lam Chung Reservoir (Lai, 2011;
AFCD, 2021c; GBIF.org, 2021; current survey); Lower Shing
Mun Reservoir (current survey); High Island Reservoir (H.T.
Cheng, pers. comm., 2021).
Native range. Russia, Japan, China, and Taiwan (East Asia).
Remarks. This species has native populations in estuaries
and lower reaches of streams locally. Reservoir populations
are conned to sites receiving water transfers from mainland
China.
Native range. Pearl River Delta endemic, South China.
Distribution. Kowloon Reception Reservoir (Lai, 2011);
Tai Lam Chung Reservoir (Lai, 2011; current study); Plover
Cove Reservoir (GBIF.org, 2021).
Remarks. Native populations inhabit estuaries and lower
courses of streams in the New Territories and Lantau Island.
However, there are several non-native reservoir populations
that are suspected to have been introduced through water
transfers from mainland China (Lai, 2011).
Mugilogobius myxodermus (Herre)
(Fig. 60, [LU])
Fig. 60. Mugilogobius myxodermus, Plover Cove Reservoir.
Distribution. Kowloon Reception Reservoir (Lai, 2011
as Mugilogobius sp.); Tai Lam Chung Reservoir (current
survey); Plover Cove Reservoir (GBIF.org, 2021; current
survey).
Native range. South China.
Remarks. Native populations are found in coastal and
estuarine areas, but reservoir populations have become
established by way of water transfers from mainland China.
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Chan et al.: Non-native shes of Hong Kong
Order Anabantiformes
Family Channidae
Channa maculata (Lacepède)
(Fig. 22B)
Distribution. Kam Tin River (Black & Veatch Hong Kong
Limited, 2005; current survey); Mai Po Nature Reserve
(WWF, 2006; WWF, 2021); Kong Nga Po area (Mott
MacDonald Hong Kong Limited, 2013); Sandy Ridge
Cemetery (Ove Arup & Partners Hong Kong Limited, 2016);
Lin Fa Tei area (Atkins China Limited, 2020); Shan Pui
River (Black & Veatch Hong Kong Limited, 2020b); Ma
Wat River, Ho Chung River, Ping Yuen River, Yuen Long
Bypass Floodway, Lam Tsuen River, Shek Kong Stream
(DSD, 2021); Ting Kok area, Wo Shang Wai area, San Tin
area, Sheung Yue River, Ng Tung River, Ping Kong area
(GBIF.org, 2021); Sam Dip Tam Stream (Tsang & Dudgeon,
2021d); Lau Shui Heung Reservoir, Shing Mun Reservoir,
Kowloon Reservoir, Kowloon Byewash Reservoir, Shing
Mun River, Lower Shing Mun Reservoir, Mui Tsz Lam
Stream, Plover Cove Reservoir, Fo Tan Nullah, Tai Lam
Chung Reservoir, She Shan River (current survey).
Native range. Japan, China, Taiwan, and Vietnam (East
Asia).
Remarks. As native populations of this species occur in
several reservoirs, the distribution records presented above
include only obvious feral populations (e.g., including many
damaged individuals and/or found in exceptionally high
abundances in channelised water courses). Historically, this
species has been cultivated in sh ponds since the 1940s
(Lin, 1949), and non-native individuals may have been
able to breed in local fresh waters or interbreed with native
populations. Channa maculata differs from Channa argus
and their hybrids by having a single stroke in the dorsal head
pattern in between the eyes (more separated from the eyes,
the larger they become) and smaller blotches on its lateral
side (for further details, see Ou et al., 2018).
