The distribution of Oreochromis niloticus was studied in Opa reservoir (Nigeria) using a graded set of gillnets while the food and feeding habits were studied using a castnet to collect the fish samples. About 90% of the fish specimens were caught near the reservoir bottom while about 69% of the specimens were caught within the inshore area of the reservoir. The species fed mainly on detritus, algae and higher plants. Feeding rhythm in O. niloticus started around 6.00 a.m. and reached a peak by 3.00 p.m. but then declined gradually until 6.00 p.m. These results can be utilized for the proper management of the fish species in the reservoi

Arawomo, G.A.O.

Komolafe, O.O.

Aquatic Commons

THE DISTRIBUTION AND FEEDING HABITS OF A
CICHLID FISH2OREOCHROMIS NELOTICUS (LINNAEUS) IN OPA
RESERVO IR, H_,E-IFE.
BY
KOMOLAtE, 0.0.
Department of Biology,
Adeyemi College of Educations,
Ondo
AND
ARAWOMO, G.A.O.
Department of Zoology,
Obafemi Awolowo University,
ABSTRACT
The distribution of Oreochromis niloticus was studied in Opa reservoir using a graded set of
gillnets while the food and feeding habits were studied using a castnet to collect the fish samples.
About 90% of the fish specimens were caught near the reservoir bottom )2vhile about 69% of the
specimens were caught within the inshore area of the reservoir. The fish species was an omnivore
and it fed mainly on detritus, algae and higher plants. Feeding in O. niloticus started around
6.00a.m. and reached a peak by 3.00p.m. but this declined gradually until 6.00p.m. These results
can be utilized for the proper management of the fish species in the reservoir.
INTRODUCTION
Oreoehromis niloticus is widely distributed in association with other fish species in tropical water
bodies (Welcornme, 1967). Field observations by Ita (1978) and Arawomo (1987) showed that O.
niloticus lived in the shallow inshore and surface waters of the Kainji Lake and in the major rivers
of the Federal Capital Territory of Nigeria. Welcomme (1970) also observed that O. niloticus
inhabited shallow swamps of Lake Victoria.
Bagenal (1978) reported fish stomach content per-se may not reflect consumers food
because some food items are digested rapidly. However, Bowman and Bowman (1980) observed
that stomach fullness and the % of empty stomach are direct evidences for evaluating feeding
periodicity. The food of fishes varied within species thereby indicating food selectivity (Pearcy and
Jullies, 1974). 0. niloticus inhabiting West African lakes fed on phytoplankton, diatoms, benthos
and detritus (Fryer and Iles, 1972; Trewavas, 1983). The report on O. nilotucus in Opa reservoir
will show how this economically important fish species can be sustained in the reservoir.
Study Area
Opa reservoir is located in Obafemi Awolowo University, Nigeria. The reservoir
has a catchment area of about 116 square kilometres -which extends from longitude 40311E to
4°39'E from latitude 7°211N to 7°351N (Figure, 1). The surface area of the reservoir is about 0.95
square kilometre while the maximum capacity is about 675 cubic metres (Figure, 2). The
catchment area is characterised by annual dry and rainy seasons. The rainy seasons extends from
April to September while the dry season extends from October to March.
The substratum of the reservoir is mainly mud and sand. Shoreline vegetation is dense with
submerged aquatic rnacrophytes, some of which eventually decompose during the rainy season.
40
Materials and Methods
A graded set of gillnets measuring 160 metres long with five different mesh sizes of 32
metres each were used to study the distribution of O. niloticus. The mesh sizes were 2.5cm,
5.1cm, 7.6cm, 10.2cm and 12.7cm with a depth of 3.78m respectively. The gillnets were set
between 6.00p.m. and 7.00p.m. in the evenings and left to fish. Fishes caught were removed
between 6.00p.m. and 7.00a.m. the following morning. The reservoir was demacated into inshore
and offshore areas as well as to three sections on the basis of the distance to the dam wall. These
were done so as to carry out random sampling of the fish species and to facilitate the description of
the actual area where fish specimens were concentrated in the reservoir.
O. niloticus specimens examined in this study were caught with castnets of 7.6cm and
2.5cm mesh sizes. The fishes were transferred to the laboratory where standard morphometric
parameters were taken. The stomach of each fish was disseced and the contents were weighed to
the nearest 0.1gm and the volume obtained by water displacement in a measuring cylinder. The
analysis of the stomach contents of each fish specimen were done by the frequency of occurrence
and numerical methods according to Hyslop (1980) and Costa et al (1992). Food identification
was done to genus and species level where p-ossible. Feeding rhythm of the species was studied on
a three hourly basis for a period of twenty four hours at each period.
Results
1580 specimens of O. niloticus caught during this study constituted 33% of all fish
specimens caught in the reservoir (Table 1). The size ranged from 11.0cm total length, 8.5cm
standard length and a weight of 38.0gm to 38.6cm, 31.4cm and 1038gm as total length, standard
length and weight respectively. Fish specimens representing 30.5% of the total catch of O.
niloticus was in the upper section of the reservoir, while 41.78% and 27.65% of the total fish
specimens were caught in the central area and close to the dam wall respectively. O. niloticus was
found to be available in all the water depths of Opa reservoir. Majority of fish specimens
constituting 90.5% of the total catch were caught in the lower part of the gillnets. The non-
concentration of the species away from the water surface was confirmed statistically (X2 Cal. 557.9
X2 tab. 76.15 df 820). 68.7% of O. niloticus were caught in the inshore area while 31.3% were
caught at the offshore area of the reservoir. This horizontal distribution when tested statistically
gave (X2 Cal. 217/6 X2 tab. 76.15 df 820), thus confirming the presence of the species at the
reservoir inshore.
Feeding Rhythm
Out of 624 fish specimens caught for the feeding rhythm experiment, 35.3% of all fish
specimens had full stomachs between 6.0a.m. and 3.00p.m. During the same period, 25.6% fish
specimens had three-quarter and 21% with half stomach fullness respectively (Table, 2). 37.7% of
the fish specimens had full stomachs between 9.00a.m. and 12.00 mid-day.
41
Table 1: Relative Abundance of Fish Species Caught in Opa Reservoir Between 1986 and
1989
42
{PRIVATE } Fish Species Number of Fish Caught %
Sarotherodon galilaeus Linnaeus 1848 38.60
Oreochromis niloticus Linnaeus 1580 33.00
Tilapia zillii Gervais 1310 27.36
Hepsetus odoe Bloch 26 0.54
mormyrus rume Cuvier and Valenciennes 4 0.09
Hemichromis ffasciatus Peters 3 0.06
Hemichromis bimaculatus Gill 1 0.02
Schilbe mystus Linnaeus 8 0.17
Heterobranchus bidorsalis Geoffrey Saint-Hilaire 2 0.04
Clarias garipeinus (Burchell) 5 0.11
Malapterurus electricus (Gmellin) 1 0.02
Total 4788 100
{PRIVATE
}Period of
Feeding
Fish
speciemn
s with
full-
stomachs
Fish
specimen
s with
3/4 full-
stomachs
Fish
specimen
s with1/2
stomach
fullness
Fish
specimens
with1/2
stomach
fullness
Fish
specimens
with nearly
empty
stomach
Total
number
of fish
Fish
percentage
(6.00-9.00)am 6 59 41 6 0 112 17.95
(9.00-12.00)pm 83 32 30 6 37 188 30.13
(12.00-3.00)pm 113 60 54 23 5 255 40.87
(3.00-6.00)pm 18 5 0 12 0 35 5.61
(6.00-9.00)pm 0 0 0 0 0.0 0 0.0
(9.00-12.00)am 0 4 0 0 0.0 4 0.64
(12.00-3.00)am 0 0 0 0 17 17 2.72
(3.00-6.00)am 0 0 6 0 7 13 2.08
Total 220 160 131 47 66 624
Percentages(%) 35.26 25.64 20.99 7.53 10.58 100
Table 2: Diurnal Feedin Rh thm of O. niloticus Cau ht in 0 a Reservoir
The number of fish with full stomach increased to 51.4% between 12,00 mid-day and 3.00p.m. in
the afternoon. The number of fish specimens with full stomachs decreased to 8.2% between
3,00p.m. and 6.00p.m. in the el,Tening. 89.4% of all fish specimens caught in Opa reservoir fed
between the hours of 6,00a.m. in the morning and 3.00p.m. in the aftenloon. O. ndoticus thus fed
during the day and the peak feeding time was 3.00p.m. in the afternoon.
Food Composition
O. ndoticus fed mostly on detritus and higher plants (Table 3). Other food itenas in the
stomach were unicellular green algae, diatoms and insect remains. O. ndoticus fed on similar food
items during the dry and wet seasons except for the addition of Synedra sp and Euglena sp. during
the rainy season. O. ndoticus selectively fed on natural food materials available in Opa reservoir.
Table 3: Stomach Content Analyses of O. nilaticas in Opa Reservoir
Discussion
During this period of study, O. nilaticus constituted 33% of the total catch of 4788 fish
specimens. In the inshore area of Opa reservoir, 68.7% of the total catch of O. ndoticus specimens
were caught and this is similar to the results obtained by Ita (1978) where 62.8% of the total catch
of O. ndoticus specimens were caught from inshore area of Kainji Lake. Gwahaba (1978)
associated inshore concentration of the cichlid fishes to the presence of breeding adults. Akintunde
(1976) and Ita (1978) attributed high percentage of O. ndoticus and S. galdaeus in inshore of
Kainji lake to the need for weed cover during spawning periods. The presence of higher plants in
the diet of O. ndoticus might also be reponsible for their concentration in inshore area of Opa
reservoir.
43
{PRIVATE }Food Items Occurrence % Nunaber
Sand grains 281 17.66 -
Detritus 408 25.64 -
Mud 203 12.76 -
Green Algae
(Unicellular)C/osteriurn .sp
17 1.07 36 () 09
Euglena sp 4 0.25 20 0.05
Synedra sp Diatoms 49 3.08 233 0.59
Navicula .sp 136 8.55 9452 24.12
Stauroneis sp 74 4.65 2268 5.79
Higher plant fragments 296 18.61 26935 68.73
Insect remains 123 7.73 246 063
Total 1591 100 39190 100
Stomach contents of O. ndoticus specimens comprised natural food materials such as
higher plants, detritus, mud, sand grains and insect remains. Such natural food items were reported
by Komolafe (1985) and Abayomi (1986) in the stomachs of Tilapia zillii and Saroherodon
gililaeus of Opa reservoir respectively. Organic deposits fed upon by O. niloticus was also
reported by Welcomme (1970) to be fed upon by T leucoshca in Lake Victoria. The organic
deposits being fed upon by fishes have been reported by Hickling (1961) to be a rich source of
crude protein. The sand grains consumed along with mud by O. niloticus of Opa reservoir as part
of its diet were also recorded as part of food items for Tdapia species in the Lagos Lagoon
(Fagade, 1971). According to him, sand grains had no nutritive value but might provide some
nutritional benefits to the fishes through their dark coating of organic materials which disappeared
during passage through the intenstine. Higher plants fed upon by O. ndoticus in this study was
reported by Trewavas (1983) as food of O. niloticus in West African water bodies. Filamentous
green algae and diatoms prominent in the diet of O. niloticus were reported by Getachew (1989) as
food of O. ndoticus in Lake Awasa, Ethiopia.
O. niloticus started feeding in the early hours of the day between 6.00a.m. nd 9.00a.m.
reaching the peak period around 3.00p.m. in the afternoon. This regular feeding rhythm was similar
to the observations of Harbott (1975) and Lowe-McConnell (1975) on O. niloticus in Lake Rudolf
where the species was reported to exhibit feeding rhythm commencing between 5.00 am and
8.00am in the morning and ceasing between 2.00pm and 8.00pm in the evening.
44
Abayomi, O.S. (1986):
Akintunde, E.A. (1976):
Aravvomo, G.A.O. (1987):
Bagenal, T.B. (1978):
REFERENCES
The distribution, food and feeding habits of Sarotherodon
galilaeus in Opa reservoir. M.Sc. dissertation of the
University of Ife, Ile-Ife, Nigeria.
The biology of Tilapia and Sarotherodon species of Lake
Kainji, Nigerian with a special reference to S. galilaeus.
M.Phil. Thesis, University of Ife, Nigeria.
The fish fauna of the rivers in the New Federal Capital
Territom Abuja, Nigeria. Ile Journal of Science Vol. 2,
Nos. 1 and 2 Pp. 37-43.
Methods for Assessment of Fis-h .Procluction
Freshwaters. Blackwell Scientific Publications, OKford.
365pp.
Bowman, R.E. and Bowman, E.W. (1980):
Diurnal variation in the feeding intensity and catchability of
silver Hake (Merluccius billinearis). Can. J Fish, Agust
Sc., 37: 1565-1572.
Coasta, J.L. Assis, C.A. Almeida, P.R., Moreira, F.M. and Coasta, M.J. (1992):
On the food of the European eel Anguilla anguilla (1-) in
the upper zone of the Tagus estuary, Portugal. J. Fish.
Biol; 41: 841:-850.
Fagade, S.O. (1971): The food and feeding habits of Tilapia species in the Lagos
Lagoon. J Fish. Biol. 3: 151-156.
Fryer, G. and Bes, T.D. (1972): The Cichlid fishes qf the great lakes of Africa. Their Biology
and Evolution. Oliver and Boyd. Edinburgh.
Gwahaba, J.J. (1975):
Harbott, B.J. (1975):
Hickling, C.F. (1961):
Hyslop, EJ. (1980):
The distribution, population density and biomass of fish in
an equatorial Lake, Lake George, Uganda, Proc. R. Soc.
Lond B. 190: 393-414.
Preliminary observations on the feeding of Tilapia nilotica
Linn. in Lake Rudolf 4fr. J Mop. Hydrobiology and
Fisheries 4(1): 27-37.
Tropical Inland Fisheries longmans Green and Co. Ltd.
London and Southampton 287pp.
Stomach content analyses - a review of methods and their
application. J Fish. Biol 17: 411-429.
45
Ita, E.0. (1978): An analysis of fish distribution in Kainji Lake, Nigeria.
Hydrobiologia 58 930: 233-244.
Komolafe, 0.0. (1985): The Biology of the cichlid Fish Tilapia zulu (Gervais) in
Opa Reservoir. M.Sc. dissertation of the University of lib,
Ile-Ife, Nigeria.
Lowe-McConnell, R.H. (1975). Fish communities in
Tropical Freshwaters Longman Group Ltd. Lond. 337pp.
Pearcy, W.G. and Jullie, W.A. (1974):
Food Habits of deep sea macrourid fishes off Oregon
Coast. Deep Sea Res. Oceanogra. Abstr., 21(1): 745-759.
Trewavas, E. (1983):
Welcomme, R.L. (1967):
Weicomme, R.L. (1970)
Tilapiine Fishes of the genera Sarotherodon, Oreochromis
and Danakiha. The Dorset Press. Dorchester. British
Museum (Natural History) 583pp.
The relationship between fecundity and fertility in the
mouth brooding Cichlid fish Tilapia leucosticta J Zool.
Lond, 151: 453-468.
Studies of the effects of abnormally high water levels on the
ecolog,y of fish in certain shallow regions of Lake Victoria.
Zool. Lond, 160: 405-436.
46


The distribution and feeding habits of a cichlid fish Oreochromis niloticus (Linnaeus) in Opa Reservoir, Ile-Ife

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The distribution and feeding habits of a cichlid fish Oreochromis niloticus (Linnaeus) in Opa Reservoir, Ile-Ife

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