The study was
carried out to evaluate length-weight relationship and condition factor of five
species of cichlids found in Eleyele Lake. Five species that were found
throughout the study period are Tilapia zilli, Tilapia guineensis, Hemichromis fasciatus, Oreochromis
niloticus and Sarotherodon melanotheron. The relationship between
the length and weight of the fish species showed that they are allometric in
growth and this implies that the fish species did not increase in weight faster
than the cube of their lengths. The mean condition factor for the five species
is 2.8 for Tilapia
zilli, 2.3 for Sarotherodon melanotheron, 2.7 for Tilapia guineensis,
2.2 for Oreochromis
niloticus and 2.1 for Hemichromis fasciatus. The study revealed that Hemichromis
fasciatus and Oreochromis niloticus and Tilapia zilli dominated the lake
during the study period.
2. Keywords: Cichlids; Condition factor; Length-Weight Relationship
are more frequent in fishes of tropical subtropical water bodies due to several
factors such as environmental variations, multiple spawning, dynamics of food
compositions, physiological changes etc. Growth of fish is a mathematical
function of length and weight and varies due to biological changes and seasonal
dynamics . The study of length weight
relationship in fishes is of primary importance in setting up equations in
estimating the number of fish landed as well as in comparison of population in
time and space. The length-weight relationship of fish is an important fishery
management tool. Its importance is pronounced in estimating the average weight
at a given length group and in assessing the relative well being of a fish
population . Condition factor compares the
well being of a fish and is based on the hypothesis that heavier fish of a
given length are better-condition . Condition
factor has been used as an index of growth and feeding intensity.
Oyo State is
completely land-locked and has no access to the sea. However, it is endowed
with natural large water surface area and its domestic fish production is
derived mainly from rivers, lakes and reservoirs (Dams) etc. Prominent among
such water bodies are those lakes built by the water corporation of Oyo State
and are located in various parts of the state (Table 1).
Others include 14 lakes built by OYSADEP (Oyo State Agric. Development
Programme): 1 by IITA: 1 by Railway Corporation: 3 by Ogun-Osun River Basin
Development Authority (OORBDA) and 1 Natural lake at Ibusogbooro in Oyo West
Local Government Area (Odo-Ogun). These lakes totaled 28 and covered a total
water surface area of 10,175.19 hectares with 1,152 fisher folks, 962 canoes as
at 1999 and 2,433.02 tonnes of fish were landed as at 2000 . Therefore, the objectives of the study are to
evaluate length-weight relationship and condition factor of five fish species
in Eleyele Reservoir and investigate the species that is abundant during the
Materials and Methods
The Study Area
study was conducted at Eleyele reservoir, Ibadan Oyo State. Nigeria. The
temperature of the area ranges from 25ᶱC-30ᶱC and the Longitude7°23'49"N,
Latitude 3°52'2"E. Eleiyele reservoir
was constructed by the Water Corporation of the old Western Region in 1939
primarily to supply water to Ibadan city by darning of the river Ona which
itself covers a distance of 62Iun from its source to the dam. It has a surface
area of 152.76ha and a storage capacity of 1550 million gallons; a maximum
depth of 12m, and a mean depth of 6.5m. Its basing is long and narrow and
divided into two main stretches, with the narrowest part slightly over 20m and
the widest slightly above 250 m. The dam receives water during the rainy season
principally from the River Ona and other associated small streams, in addition
to water from run-offs. The control of the fisheries of Eleiyele reservoir
resides in the Oyo State Ministry of Agriculture and Natural resources acting
through its Department of Fisheries. The Department of Fisheries exercises its
powers under the relevant laws to formulate by-laws and regulations for the
development, exploitation, management and protection of the fishery resources .
were procured from artisanal fishers and middlemen at the landing site.
Sampling of landed catches was done once a month for a period of six months.
The fishers used a range of fishing gear such as gill net, cast net set nets
and traps. From the catches the fish specimens that were abundant were selected
and kept in insulated containers for onward transportation to the department
laboratory for further analysis.
Length-Weight relationship and Condition Factor of fish
The total length
of the fish was measured from the tip of the mouth to the caudal fin using
meter rule calibrated in centimeters. Fish were measured to the nearest
centimeter. Fish weight was taken using a sensitive scale to the nearest gram.
The mean length and weight of the different species were used for data analysis.
between the length (L) and weight (W) of fish was expressed by equation (Pauly,
W = aLb
W = weight of fish
L = total length
(TL) in (cm)
a = constant
b = the length
The ‘a’ and ‘b’
values were obtained from a linear regression of the length and weight of fish.
The correlation ‘r’ that is the degree of association between the length and
weight was computed from the linear regression analysis.
factor (K) of the fish specimen was estimated from the relationship
K = 100W
K = condition
W = weight of fish (g)
L = length of fish (cm)
Analysis of Data
analysis was performed to determine the relationship between length and weight
3.1. Fish Species in Eleyele Reservoir
Fish species that were found
throughout the study period are Tilapia zilli, Sarotherodon
melanotheron, Tilapia guineensis, Oreochromis niloticus and Hemichromis fasciatus Other fish
species that were captured once or twice during the study period are Hespetus odoe,
Hemichromis elongates, Clarias
gariepinus, Heterotis niloticus and Tilapia galileaus.
Akinyemi et al. (1986)  observed that fishing
was done in Eleyele reservoir only during the dry season months of November to
April and from visual observation and identifications of fish landing made by
cooperative fishermen, they found out that the Cichlidae were most abundant and
were dominated by Oreochromis niloticus, TIlapia zilli and Hemichromis fasciatus. The results
obtained from this study also corroborate with the findings of Akinyemi et al. (1986)
. They also found out that in most cases,
species of Hemichromis
bimaculatus and Hemichromis fasciatus were observed to be thrown
back into the reservoir by the fishermen whenever they were encountered in the
catch but now all their catches were sold to the fish mongers.
The Length-weight relationship
of the five fish species most abundant during the study period is presented in table1. The relationship between the length and weight of
the fish species showed that they are allometric in growth and this implies
that the fish species did not increase in weight faster than the cube of their
lengths. Fish are said to exhibit isomeric growth when length increases in
equal proportions with body weight for constant specific gravity. The
regression co-efficient for isometric growth is ‘3’ values greater or lesser
than ‘3’ indicate allometric growth (Gayando and Pauly, 1997) . Several authors have reported both isometric and
allometric growth for different fish species from various water bodies. King reported
allometric growth for Tilapia species from Umuoseriche Lake. Abowei et al. (2009)  reported
isometric growth for Ethmalosa Fimbriata, Illishia
Africana and allometric growth for Sardinella. maderensis and Cynoglossus sengalensis from Nkoro
river, Niger state.
representation of the condition factor of each species studied is shown in
figs. 1,3,5,7 and 9. The condition factor ranged from 2.2 to 3.9 for Tilapia zilli,
1.7-3.0 for Sarotherodon
melanotheron, 1.8-5.3 for Tilapia guineensis, 1.8-2.5 for Oreochromis
niloticus and 1.5-2.8 for Hemichromis fasciatus. There was difference in the
condition factors for the combined fish and the monthly factor for each fish
species studied. The condition factors obtained in this study is very close
with the results obtained from other studies. Hatikakoty and Biswas (2004)  reported mean condition factor between 1.48 and
2.89 for Oreochromis
mossambicus in different seasons.
The value of condition factors
obtained in this study showed that all the species studied were in good
condition. Gayando and Pauly (1997)  reported
that certain factors often affect the well being of a fish. The factors include
data pulling, sorting into classes, sex, stages of maturity and state of the
Figure 1: Condition factor
of Tilapia zilli
Figure 2: Length-Weight
relationship of Tilapia zilli.
Figure 3: Condition factor for Sarotherodon melanotheron.
Figure 4: Length-Weight relationship for Sarotherodon
Figure 5: Condition factor for Tilapia guineensis.
Figure 6: Length-weight relationship of Tilapia
Figure 7: Condition factor for Oreochromis niloticus.
Figure 8: L-W Relationship of Oreochromis niloticus.
Figure 9: Condition Factor for Hemichromis fasciatus.
10: L-W relationship of Hemichromis
W = 777.6e-0.27TL
W = 89.63 e0.309TL
W = 424.7 e0.015TL
W = 195.3e0.015TL
W = 154.2e0.108TL
Table 1: Length-Weight relationship for the five species of Cichlids found in Eleyele reservoir
Das SK (2004) Biology of length-weight and Condition
in a Brackish water fish Liza tade (Forskal) In: Fishery Management by
Professor Arvind Kumar A.P.H Publishing Corporation 5, Ansari Road, Darya Ganj
New Delhi: 251-253.
Abowei JFN, Davies OA, Eli AA (2009)
Study of the Length-weight relationship and condition factor of five fish
species from Nkoro River, Niger Delta, Nigeria. Current Research Journal of
Biological Sciences 1: 94-98.
Bagenal TB, Tesch AT (1978) Conditions and Growth
Patterns in Fresh Water Habitats. Blackwell Scientific Publications Oxford: 75-89.
Olubowale Ojo (2002) Lake Fisheries Management in Oyo
State Pre-season training for officers handling the IFAD-Assisted Artisanal
Fisheries Development Project- Cage fish culture Trials-Second Cycle in Oyo
State Held at The Fisheries Research Laboratory complex, Premier Hotel Road,
Agodi Ibadan 1st March 2002.
Pauly D (1983)
Some simple methods for the assessment of tropical fish stock. FAO Fish Tech
Paper No 234: 52.
Akinyemi O, Ita EO, Sado EK (1986) A preliminary
assessment of the post-impoundment fisheries of Lake Eleiyele and Lake Asejire,
Oyo State, Nigeria. Kainji Lake
Research Institute 1985 Annual Report: 44-50.
Gayando FC, Pauly D
(1997) FAO ICLARM stock assessment tools (FISAT): References Manual, FAO
Computerized Information Series (Fisheries) 8: 262.
Hatikakoty G, Biswas SP (2004) Length-Weight
relationship and condition factor of Oreochromis mossambicus (Peters) from a domestic
pond, Nazira, Upper Assam in: Fishery Management by Professor Arvind Kumar A.P.H
Publishing corporation 5, Ansari road, Darya Ganji, New Delhi-110002.
Le Cren ED (1951)
The length-weight relationship and seasonal cycle in gonad weight and condition
in the perch Perca
Journal of Animal Ecology 20: 201-219.
Citation: Olubunmi A, Folake BA, Omokhafe OI (2017) Biology of Length- Weight Relationship and Condition Factor of Some Cichlids in Eleyele Lake, Oyo State, Nigeria. J Fish Aqua Dev: JFAD-122. DOI:10.29011/JFAD-122/100022