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AQUATIC RESEARCH
E-ISSN 2618-6365
70
Length-weight relationship, condition factor dynamics, and
feeding preference of Clarias batrachus (Linnaeus, 1758) from
the rivers of Bataan, Luzon Island, Philippines
Mark Nell C. CORPUZ, Roselle ROJERO, Mark Anthony OCAMPO, Emmarie PADILLA
Cite this article as:
Corpuz, M.N.C., Rojero, R., Ocampo M.A., Padilla, E. (2025).
Length-weight relationship, condition factor dynamics, and feeding preference of
Clarias batrachus (Linnaeus, 1758) from the rivers of Bataan, Luzon Island, Philippines. Aquatic Research, 8(2), 70-78.
https://doi.org/10.3153/AR25008
Bataan Peninsula State
University, College of
Agriculture and Fisheries,
Institute of Fisheries and Aquatic
Sciences, Orani Campus, Bayan,
Orani, Bataan 2112, Philippines
ORCID IDs of the author(s):
M.N.C.C. 0000-0002-2582-0772
R.R. 0009-0000-0394-4478
M.A.O. 0009-0001-6321-9355
E.P. 0009-0001-7773-7890
Submitted: 06.07.2024
Revision requested: 25.07.2024
Last revision received: 31.07.2024
Accepted: 01.08.2024
Published online: 01.02.2025
Correspondence:
Mark Nell CORPUZ
E-mail: mnccorpuz@bpsu.edu.ph
© 2025 The Author(s)
Available online at
http://aquatres.scientificwebjournals.com
ABSTRACT
There is a paucity of information on Philippine catfish (Clarias batrachus) thriving in fishery areas
in Bataan, Luzon Island, and the Philippines. The study examined the length-weight relationship
(W = aLb), condition factor, and stomach content of C. batrachus collected from two major river
systems in Bataan (Orani and Bagac Rivers), Philippines. A total of 60 fish specimens (12.4–25.5
cm) were collected using a 12-v electrofishing gear and fishing net. Although the specimens from
Orani were significantly larger than those from Bagac, the latter exhibited an isometric growth rate
(b = 3). Orani population displayed a negative allometric growth (b < 3). Female and male samples,
regardless of site variability, showed a statistically isometric growth rate (b = 3). The condition
factor of C. batrachus was K = 1.0, irrespective of site and sex variation, signifying that the popu-
lations are in good condition. Five food items were detected in Bagac, with the Gobiidae family
emerging as the predominant prey items based on number (48.89%), frequency of occurrence
(100%), and weight (72.83 %). Orani recorded three food items, primarily macroinvertebrates
(Chironomidae), accounting for 75 %N, 86.67 %O, and a frequency of 91.19%. The Index of Pre-
ponderance and Index of Relative Importance recognized Gobiidae and Chironomidae as the two
most important food items in Bagac and Orani, respectively. The baseline dataset generated from
this study is hoped to provide insights into the current population status of this important fishery
resource for improved riverine conservation management.
Keywords: Bagac, Growth coefficients, Index of preponderance, Orani, Prey items
Aquatic Research 8(2), 70-78 (2025) • https://doi.org/10.3153/AR25008
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Introduction
The Clarias batrachus (Linnaeus, 1758) populations are na-
tive to Southeast Asia and have been introduced worldwide
for fish farming (Allen, 2011). This clariid species is an air-
breathing and hardy fish that can thrive in areas where many
other fish struggle to survive. It is mostly found in freshwater
and brackish water rivers, lakes, ponds, streams, swamps,
ditches, rice paddies, and reservoirs (Froese & Pauly, 2023;
Allen, 2011). Successful aquaculture of this species provides
socio-economic sustainability for rural communities
(Debnath, 2011). Its economic importance stems from its at-
tractiveness, taste, food conversion efficiency, ruggedness,
and consumer popularity (Hossain et al., 2006; Debnath,
2011). This fish is also commonly referred to as Asian catfish
and is considered an integral part of commercial fisheries, aq-
uaculture, and home aquariums, particularly in Asia, where it
is widely consumed. In the Philippines, the wild populations
are now displaced (Paller, 2011) attributed to various factors
such as drought periods, habitat destruction, and the uncon-
trolled introduction of a larger African catfish (C. gariepinus)
that are known for fast growth and feral wild populations
(Ahmad et al., 2012). In the Philippines, it is locally known
as hito or pantat and supports communal and subsistence
fisheries in the riverine fishery areas of Bataan, Philippines
(Corpuz & Espaldon, 2023).
Despite the ecological and economic importance of C. bat-
rachus, studies on fisheries biological tools, including length-
weight relationships (LWR) and condition factors, have hit-
herto not been conducted at a local level to assess the ecolog-
ical status of this important aquatic resource. Apart from
LRW and condition factors, the gut analysis of the species
provides important insight into feeding patterns and quantita-
tive assessment of food habitats, which is also a key aspect of
fisheries management (Hyslop, 1980). Moreover, the gut con-
tent analysis helps understand the food preference of fish spe-
cies' natural history, nutritional requirements, trophic, mate-
rial and energy dynamics, food webs, food chains, and mate-
rial and energy transfers between and within ecosystems
(Manko, 2016). It also reflects habitat separation in fish as the
stomach content analysis can reveal the habitat where fish
feed (Gümüş et al., 2002). Knowledge of morphometry,
growth coefficients, food, and feeding is fundamental to un-
derstanding fish biology and trophic interactions between
species in a fish community (Blaber, 2000; Corpuz et al.,
2013; Corpuz, 2018). Similarly, these baseline datasets are
yet known for C. batrachus populations thriving in Luzon Is-
land, Philippines. Hence, the present study evaluated the
LWR, condition factor, and feeding preference of C. batra-
chus populations based on the samples collected from Ba-
taan's two separate river systems (Orani and Bagac).
Materials and Methods
Study Areas
The specimens were collected in the daytime from the east
and west coasts of Bataan, Philippines. The C. batrachus
specimens for the east portion of Bataan were collected in
Orani River, Tagumpay, Orani (14º48’46” N and 120°30’56”
E). The fish specimens for the west coast were collected in
the Bagac River (Silahis-Pag-asa, Bagac, 14º35’45” N and
120º23’47” E). Both river systems serve as a communal fis-
hing area for the local stream communities. Apart from fish-
ing, the area is often used as a water source for agricultural
purposes.
A total of 60 C. batrachus individuals (30 specimens from
Orani, Bataan, and 30 specimens from Bagac, Bataan) were
collected using 12-v electrofishing gear and scoop net from
August to November 2023. The fish specimens were immer-
sed in a phenoxyethanol solution (1 ml 5 L-1) to induce sleep
and immediately preserved in an ice box to avoid the diges-
tion of food items. The specimens were brought to the labor-
atory of Bataan Peninsula State University for further exam-
ination.
Fish Analyses
In the laboratory, the fish specimens were immersed in phe-
noxyethanol solution (0.2 ml L-1) to sleep prior to length and
weight determination. The total length (TL, measured from
the snout to the tip of the caudal fin) was measured using a
vernier calliper (0.01 cm). The wet weight of specimens was
determined using a digital weighing scale (0.01 g).
Using a scalpel, the fish specimens were incised from the
anus up to the throat to reveal the alimentary canal. The stom-
ach was exenterated from the whole alimentary canal by sep-
arating the attached organs from it and cutting it from the car-
diac area to the pyloric section. The incision was performed
in the lesser curvature of the stomach. The stomach contents
of each specimen were extracted and transferred in gridded
Petri dishes with tissue paper (no fixation). The sorted food
items were counted and identified to the lowest possible tax-
onomic level under a simple microscope. The wet weight of
the prey item was determined to the nearest 0.01 g using an
analytical balance. The volume of each prey taxa was meas-
ured by water displacement in a graduated cylinder.
Aquatic Research 8(1), 70-78 (2025) •
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Figure 1. Map of Bataan, Philippines, showing the collec-
tion sites. (A) Tagumpay in Orani and (B) Parang in Bagac
Data Analyses
The equation expressed the allometric LWR:
W = a TL b
Where W = is the weight (g) of an individual fish; TL = is the
total length (cm) of fish individuals; a is the intercept, and b
is the slope. The transformation of fish length and weight as
Log w = log a + b x log (TL) was used to compute the a and
b (Froese, 2006). The fish body condition factor was calcu-
lated using the equation by Fulton (1902).
K = W/LWR
K = condition factor, W = weight (g) of fish, and LWR =
Length-weight relationship.
The growth rate pattern of the fish (allometric or isometric)
as expressed in the value of b (slope) was tested for theoreti-
cal value for isometry when b was significantly equal to 3;
growth was regarded as isometric if b < 3 is negative allome-
tric, and b > 3 is positive allometric (Santos et al., 2020) (t-
test, P < 0.05).
The relative measures of stomach content were evaluated
quantitatively using three methods of occurrence (O%), de-
fined as the number of stomach samples in which prey occurs
expressed as a percentage of all stomachs; numeric percent-
age (N%) was defined as the number of individual in each
prey categories recorded for all stomachs with the total ex-
pressed as a percentage of the total individuals in all prey cat-
egories and wet weight percentage (W%) defined as the wet
weight of each prey recorded for all stomachs, with the total
expressed as a percentage of a total wet weight of all prey
categories (Hyslop, 1980). The partial fullness index was
computed to compare the variation of the food found in the
stomach among sampling sites. Two indices of dietary im-
portance were also calculated to evaluate the prey importance
through the equations:
• Index of Preponderance (IOP) (Natarajan and
Jhingran 1962); IOP = %V.%F÷∑%V.%F*100;
• Index of Relative Importance (IRI) (Pinkas et al.,
1971): IRI = %F (%N + %V); %IRI = (IRI/ΣIRI)
*100.
The correlation between the prey item biomass and TL of C.
batrachus was predicted using the transformed log10 (x+1),
and the relationship was determined by a non-linear regres-
sion function: f = axb, where a = coefficient, x = TL, and b =
slope.
A
B
A
B
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Results and Discussion
Total Length and Weight
The mean and SD of the total length and weight of C. batra-
chus specimens are summarized in Table 1. The TL variation
between C. batrachus populations was significant (t = 3.62;
P < 0.01), with Orani (22.15 ±2.98 cm) having longer TL than
Bagac (19.25 ±3.20 cm). The length of female samples in
Orani (23.36 ±2.29 cm) was significantly larger than the male
(20.56 ±2.29 cm). While in Bagac, the length of the female
(19.56 ±3.11 cm) was slightly longer than the male (18.64 ±
3.46 cm). Inter-sexual variation in TL was not significant (t =
1.66; P < 0.05), albeit the site-sex factor was found to be sta-
tistically different (F = 7.2; P < 0.01).
The weight of specimens from Orani (82.65 ±30.81 g) was
significantly heavier than in Bagac (52.06 ±24.79 cm) (t =
4.24; P < 0.01). The weight of female specimens in Orani
(92.41 ±35.15 g) was heavier than the male specimens (69.89
±19.66 g). While the weight of female specimens in Bagac
(53.01 ±24.16 g) was slightly heavier than the male (48.82
±28.51 g), sexual differentiation was not significant (P >
0.05).
Length-Weight Relationship and Condition Factor
The summarized dataset of LWR and the condition factor of
C. batrachus is presented in Table 2. The observed growth
coefficient of Bagac (b = 3.11, SE = 0.284) was isometric de-
spite a slight deviation from b = 3.0. On the other hand, a
negative allometric growth rate was observed in Orani popu-
lations (b = 2.55, SE = 0.200). Male and female populations
exhibited isometric growth coefficients (male b = 2.963, SE
= 0.285; female b = 2.9458, SE = 0.202). For Bagac, the male
and female growth coefficients were isometric (male b =
3.40; female b = 3.04), while in Orani, male and female had
negative allometric (male b = 2.45; female b = 2.73). Scatter
plots of the relationship between the length and weight of
specimens are illustrated in Figures 3 and 4.
Table 1. Descriptive statistics of Clarias batrachus in Orani and Bagac, Bataan, Philippines
Collection
Sites Sex n
Total Length (cm) Body Weight (g)
Min Max Mean ± SD Min Max Mean ± SD
Orani
F 17 18.43 28.79 23.36 ±2.92a 51.05 163.49 92.41 ±34.59a
M 13 15.76 23.27 20.56 ±2.29a 30.79 92.21 69.89 ±19.66ab
Bagac
F 20 14.14 23.27 19.56 ±3.11b 19.21 91.74 53.01 ±24.16b
M 10 13.73 23.27 18.64 ±3.41b 19.24 100.72 48.82 ±28.51b
Similar letters indicate no statistical difference in each row at a 5% confidence level. a > b.
Table 2. The LWR parameters and condition factor of C. batrachus in Orani and Bagac, Bataan, Philippines
Collection Sites Sexes n
Growth coefficients
Condition Factor
a b r2
Orani Female 17 0.02 2.73 0.83 0.99 1.01
Male 13 0.04 2.45 0.85 1.04
Bagac
Female 20 0.01 3.04 0.81 1.01
1.01
Male 10 0.01 3.40 0.93 1.01
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Length (cm)
12 14 16 18 20 22 24 26 28 30
Weight (g)
0
20
40
60
80
100
120
140
160
180
Orani male
Orani female
Bagac m ale
Bagac femal e
The overall computed condition factor value showed no sig-
nificant deviation from K = 1.0 (Table 2), signifying that the
two populations are well-being. Moreover, regardless of sex,
the K scores of specimens from the two sites were not signif-
icantly different (F = 0.002; P > 0.05). The result of the pre-
sent study is similar to the results obtained by Rosli and Isa
(2012), wherein the growth of Plicofollis argyropleuron from
the Northern Part of Peninsular Malaysia was also observed
to be isometric. A similar result was also reported by Fafi-
oye and Ayodele (2018), where Coptodon zillii, Brycinus
nurse, and Oreochromis niloticus from Oyan Lake, Nigeria,
were observed to have negative allometric growth coeffi-
cients. Similarly, the condition factor (K) recorded in the
above-stated fishes was greater than one (>1). Several factors
have been noted to influence the LWR in fishes, including
season, habitat, gonad maturity, sex, diet and stomach full-
ness, health, and preservation techniques, which can contrib-
ute to the different b values of the same species from various
areas (Perez & Ignacio, 2019).
The LWR is usually used to determine the stock assessment,
population dynamics, growth pattern, general health, habitat
conditions, life history, fish condition, and morphological
characteristics (Falsone et al., 2022; Jisr et al., 2018; Santos
et al., 2020). A recent study revealed that the male and female
C. batrachus in Orani had negative allometric (b < 3). Nega-
tive allometric occurs when the fish's body length increases
faster than the fish's body weight, meaning these fish become
lighter with increasing size (Mazumder et al., 2016). At the
same time, the population from Bagac revealed that the male
and female C. batrachus had isometric growth (b = 3), where
the weight and length of the organism increased at the same
rate.
The condition factor of a fish reflects physical and biological
circumstances and fluctuations, such as feeding conditions
and parasitic infections (Datta et al., 2013). It is an important
tool that provides information on fish inter-population varia-
tion in growth patterns and condition factors (De Leon et al.,
2017; Santos et al., 2020). The K values for C. batrachus in
Orani and Bagac observed in the study are similar to the ob-
servation by Abobi (2015). This study also provides evidence
of good overall health and welfare of C. batrachus.
Prey Composition and Food Analysis Indices
Sixty stomachs were examined in two sampling sites, and no
empty stomach was recorded. In Bagac, five food categories
were identified in the stomach: fish, gastropods, insects, plant
materials, and crustaceans. Large prey items, particularly
Glossogobius giuris, a common species of goby found in the
river of Bagac, dominated the diet, comprising 48.89% by
number (%N) and 100% by frequency of occurrence (%O).
This was followed by crustaceans with 26.67 %N and 60 %O,
plant materials with 11.11 %N and 33.33 %O, insects with
8.89 %N and 26.67 %O, and the least amount in the diet was
gastropods with 4.44 %N and 6.67 %O. On the other hand,
only three categories were identified in Orani comprising in-
sects with 75 %N and 86.67 %O, gastropods with 16.67 %N
and 33.33 %O, and plant materials with 8.33 %N and 13.33
%O.
Figure 3. Scatter diagram plot of male and female Clarias batrachus length-
weight relationship from Orani and Bagac, Bataan, Philippines.
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Length (cm)
14 16 18 20 22 24 26 28 30
Weight (g)
20
40
60
80
100
120
140
160
180
Length (cm)
12 14 16 18 20 22 24
Weight (g)
0
20
40
60
80
100
120
Figure 4. Scatter diagram plot of the length-weight relation-
ship of Clarias batrachus in (A) Orani and (B) Bagac,
Bataan, Philippines
The ranking of prey items based on IRI and IOP is presented
in Table 3. The most important food item in Bagac, which
comprised 76.61 %IRI and 83.13 %IOP, was fish prey item.
While in Orani, insects were recognized as the most relevant
food items comprising 94.26 %IRI; in terms of %IOP, it ap-
peared with 94.26%.
Diet Variation
The relationship between number, volume, and occurrence
displayed a degree of diet variation among the C. batrachus
specimens (Table 5). In Bagac, fish was recognized as the
major prey item by number and exhibited the highest occur-
rence and volume rate in the gut content. In Orani, insects
were determined as the major prey item by number and ex-
hibited the highest volume and occurrence rate.
A fish-based diet was the dominant prey item of Bagac pop-
ulations (48.89 %PFI), but no fish consumption was recorded
in Orani. The proportion of crustacean prey items was 26.67
%PFI, and there was no crustacean intake in Orani. On the
other hand, insects were recorded as the major prey in Orani
samples (75 %PFI); on the contrary, they ranked second to
the least (8.89 %PFI) on the other site. Plant materials (11.11
%PFI) and gastropods (4.44 %PFI) were also recorded in
Bagac. The Orani specimens also consumed gastropods (8.33
%PFI) and plant materials (16.67 %PFI). There was no sig-
nificant relationship between the TL (cm) of the fish and prey
item weight (g), as the amount of food consumed by the fish
was not dependent on its length (r2 = 0.33, b = 10.24) (Figure
6).
Table 3. Index of Preponderance (IOP) and Index of
Relative Importance (IRI) of C. batrachus populations from
Bagac and Orani
Prey items IOP Rank IRI Rank
Bagac
fish
83.13
1
76.61
1
crustaceans
15.61
2
18.68
2
insects
0.57
5
1.81
4
gastropods
0.07
4
0.22
5
plant materials
0.63
3
2.68
3
Orani
fish
0
0
0
0
crustaceans
0
0
0
0
insects
97.41
1
94.26
1
gastropods
0.69
3
1.09
3
plant materials
1.91
2
4.65
2
The feeding habit of C. batrachus, a carnivorous fish species,
reveals a high preference for preying crustaceans, insects, and
teleost fishes. A similar observation was reported by Sakhare
and Chalak (2014), wherein C. batrachus populations in In-
dia preferred small fishes and insect larvae as the primary
food items. The small fish prey items found in Bagac speci-
mens signified the importance of small fishes in the river to
sustain native catfish protein source requirements. The pre-
sent findings agreed with the observation of Ramesh and
Kiran (2016) and several authors in South Africa that indi-
cated that the C. gariepinus did not rely only on offshore
fishes and benthic invertebrates at high lake levels. However,
they readily switched their feeding to littoral fishes and inver-
tebrates when these became abundant (Wakil et al., 2014). On
A
a = 0.03
b = 2.55
r2 = 0.85
B
a = 0.01
b = 3.11
r
2
= 0.88
Aquatic Research 8(1), 70-78 (2025) •
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76
the other hand, nourishment for the growth of Orani samples
is highly dependent on insects. This change in feeding habits
might be attributed to the absence of other fish species in the
Orani River caused by anthropogenic activity such as the il-
legal use of chemical compounds (e.g. sodium) for fishing,
including other environmental perturbations (Romero et al.,
2016: Flores et al., 2015).
Figure 5. A stack bar representation of the main diet com-
position of Clarias batrachus is expressed as a distribution
of the Partial Fullness Index among sampling sites
Figure 6. Relationship of prey item biomass with the total
length of Clarias batrachus
The present study revealed that the amount of prey items in-
gested by C. batrachus is not size-dependent. It is highly ev-
ident that C. batrachus is a voracious feeder that consumes a
large amount of food regardless of its size, as shown in Figure
6. This contradicts the study of Admassu et al. (2015), who
stated that the proportion of insects and zooplankton de-
creased with the increase in fish size, while fish prey in-
creased with the increase in Lake Babogaya.
Although the study is limited to a few individuals, to the best
of our knowledge, it provided vital datasets of the population
profile of C. batrachus, which can serve as a baseline refer-
ence for future investigation. There is a need to reduce fishing
pressure (Romero et al., 2016) and other aquaculture activi-
ties (Flores et al., 2015) impacting the ecological integrity of
the river ecosystems, which may eventually affect the C. ba-
trachus and other native fish populations. This study hoped
to enlighten the local community on the status and growth
condition of C. batrachus. It could serve as a basis for the
conservation management program for the two studied rivers.
Conclusion
Despite being larger in length and weight, the growth coeffi-
cient of Orani populations had negative allometry compared
to the isometric growth rate of those from Bagac. However,
the good condition factor of the two populations is similar,
attributed to their biological capacity to adapt to varying hab-
itat conditions. Both populations were in good condition, al-
beit their growth coefficients were dissimilar, indicating mor-
phological plasticity to adjust to external environmental pres-
sures.
Further investigations on potential factors (diet, physico-
chemical, and anthropogenic disturbances) affecting LWR
and condition factors are necessary. Increasing sample size
and inclusion of other populations from other river systems
can improve the robustness of LWR and condition factor
data. Further investigation is also suggested to assess the in-
fluence of sexes and seasonality on the feeding pattern dy-
namics of C. batrachus. An additional study can also be done
to understand further the dietary aspects and feeding habits of
C. batrachus. Given the importance of stomach content anal-
ysis, future investigation should also be extended to other fish
species, especially indigenous ones, to provide scientific in-
formation for their management.
Log Prey Item Weight
1.1 1.2 1.3 1.4
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
r2 = 0.33
Y = 0.0097x10.24
Log Total Length (cm)
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Compliance with Ethical Standards
Conflict of interest: The author(s) declare no actual, potential, or
perceived conflict of interest for this article.
Ethics committee approval: The Animal Care and Use Com-
mittee of Peninsulares Ethics Review Board of the Bataan
Peninsula State University (REDO.PROJ.OC026) approved
protocols for animal experiments.
Data availability: Data will be made available on request.
Funding disclosure: No funding provided.
Acknowledgements: The authors extend their gratitude to
BPSU-RDO, DOST, and Iskolar ng Bataan for partially fund-
ing this study; they expressed reverence to the local fisher-
folks of Tagumpay in Orani and Parang in Bagac for their
assistance during fish collection and to the anonymous re-
viewers who provided constructive comments and recom-
mendations.
Disclosure: -
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