Breeding Behaviour and Embryonic Development of Koi Carp (Cyprinus carpio)

Abstract

Induced breeding experiments of Nikishigoi (koi carp), Cyprinus carpio were conducted in mature males and females by administrating a single intramuscular injection of ovaprim at a dosage of 0.3 mL/kg weight. Spawning was observed six hrs after the injection at ambient temperature (26-28oC). The fertilized eggs were adhesive and transparent with diameter ranging between 0.9 mm and 1.10 mm. Incubation period was 73.00hrs. The hatchlings were transparent and measured 2.7-2.9 mm, with a large oval head, a well defined yolk sac and short tail. The yolk got fully absorbed within 3 days and by this time mouth formation was complete and the larvae started exogenous feeding. After 20 days the length of fry ranged between 10 mm and 12 mm and after 35 days length of the fingerlings ranged from 30-35 mm and appeared just like an adult in all respects except sexual maturity.

Full text

Taiwania, 52(1): 93-99, 2007
Breeding Behaviour and Embryonic Development of Koi Carp
(Cyprinus carpio)
M. A. Haniffa(1,2), P. S. Allen Benziger(1), A. Jesu Arockiaraj(1), M. Nagarajan(1) and P. Siby(1)
(Manuscript received 27 January, 2006; accepted 12 April, 2006)
ABSTRACT: Induced breeding experiments of Nikishigoi (koi carp), Cyprinus carpio were conducted
in mature males and females by administrating a single intramuscular injection of ovaprim at a dosage of
0.3 mL/kg weight. Spawning was observed six hrs after the injection at ambient temperature (26-28oC).
The fertilized eggs were adhesive and transparent with diameter ranging between 0.9 mm and 1.10 mm.
Incubation period was 73.00hrs. The hatchlings were transparent and measured 2.7-2.9 mm, with a large
oval head, a well defined yolk sac and short tail. The yolk got fully absorbed within 3 days and by this
time mouth formation was complete and the larvae started exogenous feeding. After 20 days the length
of fry ranged between 10 mm and 12 mm and after 35 days length of the fingerlings ranged from 30-35
mm and appeared just like an adult in all respects except sexual maturity.
KEY WORDS: Breeding behaviour, ontogenic events, koicarp.
INTRODUCTION
Koicarp, (Nishikigoi) were developed from
colour variants of the common carp Cyprinus carpio,
in Japan during the Tokugawa period (17-19 century).
They are basically delicate but very peaceful towards
other occupants and hence well suited to aquarium
setup. They grow up to 100 cm length with an elongate
body measuring 3 to 4 times less in height than length.
In their natural habitat, koicarp live up to 15-24 years
(Kuroki, 1981). Males are known to live longer than
females. In the present investigation induced breeding
techniques, breeding behaviour and ontogenic events
of koi carp are discussed since these aspects may be of
great help to the farming community venturing into the
breeding and culture of ornamental fish species.
MATERIALS AND METHODS
Mature healthy koicarp brooders (200-250 g), two
males and one female were selected by sexual
dimorphism for breeding experiments (Fig. 1A).
Female is usually easier to spot, as the belly of a
mature female is generally plump, whereas male
remains streamlined and more torpedo shaped. When
males are ready for spawning, they develop breeding
tubercles on the head and pectoral fins, principally
___________________________________________
1. Centre for Aquaculture Research and Extension (CARE), St.
Xavier’s College, Palayamkottai 627 002, Tamil Nadu, India.
2. Corresponding author. Email: haniffacare@hotmail.com;
rihani2003@yahoo.co.in
*This article is adopted from Zoological Taiwanica which was
joined into Taiwania since 2006.
along the bones of the fin rays. These are used during
breeding, when the male nudges the female with its
head and fins to induce her to spawn. Koi generally
prefer to spawn around dawn but they may also spawn
throughout the day.
In the present study spawning was induced by
intra-peritoneal injections of ovaprim (Fig. 1B) at a
dose of 0.3 mL/kg body weight (Haniffa and Sridhar,
2002). The breeding set was released into cement
breeding tanks (1mx1mx1m) after the hormonal
administration. Aquatic macrophytes like Hydrilla
verticillata and Eichhornia crassipes were introduced
into the breeding tank for hiding purposes as well as
holding the adhesive eggs (Haniffa and Sridhar, 2002).
The breeding behaviour of brooders was observed
every hour after the injection.
Spawning activity started immediately after the
injection and lasted for about 1-8hrs. The courtship
took place at the bottom of the breeding tank. After the
first impulse of excitement, the males made
advancement towards the female (Fig. 1C). Both the
males showed participatory behaviour. Males
followed the female touching it frequently. A special
behaviour was noticed in males to attract the female
for courtship by encircling the female in order to retain
her in a given area (Fig. 1D). The excited male came
closer to the female, but the female remained quite
passive moving gracefully avoiding the approaching
male. But the active male chased the female and
generally swam underneath her. Often the active male
obstructed the path of the female (Fig. 1E) so that it
cannot avoid the male and often touched the

94 TAIWANIA Vol. 52, No. 1
Fig. 1. A: Breeding set. B: Intraperitoneal injection. C & D: Male chasing the female. E: Coutship behaviour.
F: Male touching the head of female. G: Male hitting vent of female. H: Adhesive eggs.
A B
C D
E F
G
H

March, 2007 Haniffa et al.: Cyprinus carpio 95
vent of the female (Fig. 1F), and frequently touched
the head of the female also (Fig. 1G). During mating
their dorsal fins were frequently exposed above the
water surface and there was much splashing of water
and pursuing from one area to another.
During spawning the males were aligned on
either side of the female and rubbed their body
against the female and released the milt. The
adhesive eggs were deposited on submerged
vegetation (Fig. 1H) and were fertilized externally.
When they have finished spawning, the female hang
head down, respiring heavily. After spawning the
male and female remained calm in one corner of the
tank and did not show any signs of hostility when the
eggs were colleted. Koi are not good parents and
unless they are separated from the eggs they begin to
eat the eggs.
Fertilized eggs were collected with the help of a
dropper and were reared at a density of 30/cement
tank (3x1x1 m) provided with well-aerated water
(D.O: 5.4-5.8 mg/L, pH: 7.2-7.4; temperature: 26 -28
℃). Larvae were fed with zooplankton (rotifers and
moina) two times (at 8.00 and 16.00 hrs) daily ad
libitum after yolk absorption. Samples of eggs before
fertilization and at every 30-min interval were taken
for further studies. Descriptions of the developing
stages were made by examining live specimens under
Nikon Eclipse E 400-UIII microscope and
microphotographs of the developmental stages of
eggs (Fig. 2) and larvae were taken (Haniffa et al.,
2003).
RESULTS AND DISCUSSION
Fish farmers are much less familiar with the
culture of koicarp because of the lack of breeding and
feeding techniques and non-availability of seeds
(Meehan, 2002). In the present study, spawning was
noticed 6hrs after the injection. The fertilized eggs of
koi carp were adhesive, demersal and spherical in
nature. Since the egg envelope is thick, transparent
and sticky, observations on the developmental stages
are difficult (Kovac, 2000). Changes in structure
emphasize the thresholds between embryonic, larval
and post-larval development from the onset of
cleavage or epiboly, or at the time of organogenesis,
respectively (Kovac, 2000; Carlos et al., 2002). The
eggs were deposited singly and were highly adhesive
throughout the incubation period. Due to the adhesive
nature of the egg, considerable debris adhered to the
capsule of the egg. The yellowish white egg capsule
was transparent, while the yolk was pale yellow or
green and granular. The eggs became translucent as
development progressed. The diameter of the
fertilized egg capsule ranged between 0.9 mm and
1.10 mm while the yolk sphere ranged from 0.6-0.8
mm. The incubation period of eggs depends largely
on water quality parameters such as salinity and
temperature (Kuo et al., 1973; Liao, 1975). In the
present study the eggs hatched 72hrs after
fertilization at a water temperature of 26-28℃.
Although a true metamorphosis is not generally
described for fishes, the term hatchling, larvae and
post larvae are used to indicate different stages of
development from hatchling to fingerling stage
(Boglinoe et al., 1992). In the present study the
developmental stages of koi carp were divided into
six stages. viz., embryo, hatchling, larva, post- larva,
fry and fingerling (Jhingran and Pullin, 1985) and
each stage was characterized by typical anatomical
and physiological features. A summary of the
important ontogenic events and structure is presented
in Tables 1 & 2.
The cleavage was typically meroblastic and the
first cleavage occurred (2-celled stage) within 20 min
after fertilization followed by the second cleavage,
which was completed 30 min after fertilization. The
16-celled stage reached after 39-40 min of
fertilization. The yolk invasion started after 3 hrs of
fertilization and completed after 5.26 hrs of
fertilization. The head and tail ends of the embryo
became distinguishable during yolk plug stage. Yolk
invasion was over and the blastopore was almost
closed. The notochord was clearly seen at 14hrs after
fertilization and at that time 22 somites were seen and
lens formation was started and heart formation was
almost complete. Blood circulation commenced over
the yolk into the rudimentary heart lying anterior to
the yolksac and 89-93 heartbeats per minute were
noticed at this stage. After 24 hrs of fertilization the
caudal region was detached from the yolk mass and
became free. Two otoliths were seen in the otic
vesicle and 130-140 heartbeats per minute were
observed. In the final stage of embryonic
development, the growing embryo occupied the
entire previtelline space; it exhibited frequent
twitching movement by lashing the tail against the
egg capsule. After a pause of few seconds, this
frequent movement suddenly culminated in a violent
jerk breaking the previtelline membrane and the
hatchling emerged with tail first.
Hatching occurred 32-34hrs after spawning and
the hatchlings were transparent characterized by the
presence of an almost round yolk sac. The hatchlings
ranged between 2.7 and 2.9 mm in length and tried to
hide in any refuge they find. At this stage of
development they have no swim bladder, mouth or
vent. They breathe by absorbing oxygen through the
fine blood capillaries that surround the yolk sac,

96 TAIWANIA Vol. 52, No. 1
Fig. 2. A: Fertilized egg. B: Formation of two blastomeres. C: Eight cell stage. D: Morula stage. E: Eight hours old
embryo. F: Eighteen hours old embryo. G: Twenty hours old embryo. H: Thirty hours old embryo. I: Thirty six
hours old embryo. J: Seventy one hours old embryo. K: Just hatched larva. L: One day old larva. M: Fifteen days
old fry. N: Thirty five days old fingerlings.
A B C
D E F
G H I
J
K
M
L N

March, 2007 Haniffa et al.: Cyprinus carpio 97
Table 1. Embryonic development of koicarp.
Time after fertilization (hrs). Progress in embryonic development
0.40 Blastodic formation
1.00 2 celled stage
1.30 4 celled stage
1.50 8 celled stage
2.20 16 celled stage, two tires
4.40 Morula
7.30 Germinal ring formed
11.40 Half, yolk invasion completed.
18.00 Yolk invasion completed.
24.00 Cephalic region broadened with distinct fore brain
30.30 14 somites; cephalic region broadened
36.25 16-18 somites; optic lens starts differentiating
42.20 embryonic fin fold formed; gut differentiation started
49.00 22-25 somites, lens formed in the eye; heart formed; blood circulation commenced, embryo showed slight
movements; 89-93 heartbeats / minute.
63.15 The embryo encircles the whole of the yolk; vigorous twitching movements seen.
68.20 Lens fully formed, pectoral fin buds seen; 130-140 heart beats / minute; 2 otoliths in otic vesicle.
71.20 Hatching started.
73.30 Hatching completed.
Table 2. Larval Development of Koi carp.
Larval age (days) Length (mm) Characters
Just hatched (Hatchling) Transparent with heavy yolk
1 2.7-2.9 Transparent; fin fold originates and heavy ovoid yolk sac.
3 5.0-5.4 Yolk sac absorbed; started exogenous feeding; eye pigmented.
6 5.8-6.0 Yellow pigments on the body and a silvery band on the lateral sides
15 6.8-7.0 Fin rays differentiated; pigmentation gets dark
20 12-14 Pigmentation started; various colour combinations noticed.
35 24-32 Fin rays complete; started feeding artificial feed, colouration more conspicuous.
which are still attached to the gut. The head of the
hatchling was noticed above the yolk sac and the
brain was clearly visible. After 6-8 hrs of hatching the
fin folds were seen continuously around the tail.
After 2 days the hatchlings showed free movement
and after 3 days of hatching the larvae started
exogenous feeding and are fed with finely sifted
zooplankton (Jameson and Santhanam, 1996) in spite
of the presence of little yolk sac as Balon (1985)
defined this stage as eleutembryonic.
Autonomous feeding and morphological
changes characterized the larval stage. A relatively
broad space appeared between the head and anterior
margin of the yolk sac. The yolk sac was elongate,
oval in thorasic region and became cylindrical in
abdomen and occupied about 1/3 of the body from
the anterior end. At this stage the outline of the brain
in the cranial cavity could clearly be seen under a
microscope. When 8hrs old the vent and gill
rudiments were formed. Gut was straight to slightly
curved in anterior portion. Air bladder was shallow,
behind pectoral region, which develop into two
chambers in the post larval stage. Pigmentation was
more pronounced throughout the head and body. The
larvae attained free movement with the help of fins
when 8 hrs old. The larval development is
summarized in Table 2.
Hubbs (1943) defined post-larva as the stage that
began immediately after absorption of the yolk sac
that last as long as the structure and form are unlike
that of fry. The pectoral fin was differentiated and
was in the form of a flap just behind the operculum; at
this time sidewise movement of the larvae
commenced. Two chambered air bladder was seen at
this stage. After 7 days the colour of the post-larvae
was lemon yellow and they attained 4.0-4.5 mm
length. By this time the yolk was completely
absorbed and the larvae began wandering in search of
food.
Metamorphosis from post larva to fry stage took
place after 15 days. Most of the fry were lemon
yellow in colour whereas some of them showed black
and orange colouration. At this stage the length of the
fry ranged between 7-8 mm and they gradually
resembled the adults in external features. The koi fry
have only one fin, encircling the posterior end of the
body. As they grow they developed paired fins,
mouth and other organs. The young koi swim up to
the surface and take two or three gulps of air, which
they force into their swim bladder.
After 35 days of hatching the fingerling stage was
noticed. At this stage the fingerlings ranged between
15-17 mm in length, with 8 branched rays in the
dorsal fin and 7-9 in the caudal fin. Fins were well

98 TAIWANIA Vol. 52, No. 1
developed with 17-18 pectoral fin rays, 17-21 pelvic
fin rays and 5-6 anal fin rays. They are entirely
covered by scales and appeared just like an adult.
Mouth is terminal with well-developed jaws and
teeth. Changes in the pattern of the entire structure of
an organ in relation to the environment are decisive
for evaluating the developmental patterns of species
(Balon, 1999).
CONCLUSION
The high fecundity, short embryonic period and
fast development of the fish suggest that koi are
suitable species for commercial culture. The breeding
technology discussed in the present paper may be
taken as the base material for breeding this wonderful
fish.
ACKNOWLEDGEMENTS
The authors are grateful to Indian Council of
Agricultural Research, Department of
Biotechnology, Department of Science and
Technology, Ministry of Environment and Forest,
University Grants Commission and Council of
Scientific and Industrial Research for the
infrastructure provided under various projects to
establish Centre for Aquaculture Research and
Extension at St. Xavier’s College. Thanks are also
due to Rev. Dr. A. Antonysamy , S.J., Principal of St.
Xavier’s College, Palayamkottai for providing the
necessary facilities to carry out this study.
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Dordrecht, Netherlands. pp.13-28.
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March, 2007 Haniffa et al.: Cyprinus carpio 99
錦鯉的繁殖行為及胚胎發育
M. A. Haniffa(1,2), P. S. Allen Benziger(1), A. Jesu Arockiaraj(1), M. Nagarajan(1) and P. Siby(1)
(收稿日期：2006 年1月27 日；接受日期：2006 年4月12 日)
摘 要
錦鯉 (Cyprinus carpio) 人工繁殖是將成熟的雌魚以肌肉注射的方式注射一劑
ovaprim (每公斤魚體重注射 0.3 mL)。在 26-28℃的溫度下，注射六小時後即會產卵。受
精後的卵呈透明狀具黏性，直徑在 0.9 mm 到1.10 mm 之間。73 小時後仔魚即會孵化，
魚苗體長 2.7-2.9 mm，身體呈透明狀，頭卵圓型，卵囊相當完整，尾巴很短。卵黃在三
天內會被吸收，在這期間，仔魚口部發育完全後會開始覓食。20 天後，仔魚可長到 10 mm
到12 mm，35 天後，稚魚體長 30-35 mm，此時的錦鯉除了尚未性成熟外，樣子已和成
魚相似。
關鍵詞：繁殖行為、個體發生、錦鯉。
___________________________________________________________________________
1. Centre for Aquaculture Research and Extension (CARE), St. Xavier’s College, Palayamkottai 627 002, Tamil
Nadu, India.
2. Corresponding author. Email: haniffacare@hotmail.com; rihani2003@yahoo.co.in