Age And Growth Of An Ecotype Cichlid “Wesafu” In Epe Lagoon, Lagos, Nigeria

A sample of 150 specimens of “Wesafu” in the size range of 78mm and 414mm were collected from Epe Lagoon. The period of collection spanned August to November 2003 and April to Ma y 2004 for age and growth pattern determination of this Ecotype Cichlid of Epe Lagoon. 900 scales were examined and another 232 rejected/discarded because they were regenerated or irregular. Growth rings were counted and scale radii measured. The study showed a mean range of observed lengths to be 181±12.5; 265 ± 11.6; 305 ± 1.6 and 337 ± 3.4 for the successive years of growth. The most rapid growth in length occurred during the first year in life [181mm, (+1yr.)] thereafter decrease to only 32mm in the fourth year (+4yr.). The T-test suggests that there was no significant difference between mean back-calculated body length of male and female samples for age 1+ to 3+. However, in the age group 4+, male specimens were significantly larger than the female. The fact that the fish is highly demanded and commands premium price may result in over exploitation. This explain why only 5 of the 150 specimens were of the age 4+, representing only 3.33% of total specimens which raises serious conservation question and the need for domestication and aquaculture of this highly valued fish in Lagos, Nigeria. Keywords: Age and Growth, Ecotype Cichlid, Epe-Lagoon, NigeriaGlobal Journal of Agricultural Sciences Vol. 7 (1) 2008: pp. 105-10

The use of cold shock in inducing triploidy in African mud catfish (Clarias gariepinus)

study was conducted to induce triploidy in African mud catfish Clarias gariepinus using cold shock. The fertilized eggs were exposed at one temperature regime of 0°C with varied shock treatments of 0, 15, 25 and 30 min. Some 3 min after fertilization, the success of triploidy was determined by the presence or absence of bent trunk in the fry as reported by (Aluko et al., 1997). The shock duration of 25 min at 0°C gave the best result of 55% hatch with survival at the end of the exposure regime of 43.5%. Shock exposure of 30 min gave 30% hatch while 15 and 20 min exposure were poor at 15% hatch

Biochemical Characterization of an ecotype cichlid from Epe Lagoon ‘Wesafu’ and Oreochromis niloticus using Sodium dodecyl sulphate polyacrylamide gel electrophoresis

The abundance of a yet to be identified cichlid in Epe Lagoon commonly referred to as Wesafu and the large size/weight it attains in the wild elicited interest in the fish for domestication, culture and possible species identification and naming. Characterization of Wesafu and O. niloticus biochemically using SDS-PAGE was carried out to analyze protein mixtures in the two species qualitatively and to determine their relative protein  molecular mass. After centrifugation for 15min at 1000 rpm, blood sera from the two species were electrophoretically run simultaneously on 5.5% SDS polyacrylamide gel following the procedure of [Avtalion et al., (1976); Betiku and Omitogun, (2006)]. After electrophoretic separation, the gel was stained, destained, sealed in polythene bags and refrigerated. Gels produced were scored visually with presence (1) or absence (0) of band  classifications. Frequencies were determined by direct counting while genetic interpretation was based on frequency and relative banding intensity. Distinct bands (genetic markers) were observed between the two species. While Wesafu had between 10 and 11 bands, 9 bands was  recorded for O. niloticus. The 11th band in Wesafu was identified as a post albumin which is absent in O. niloticus. In O. niloticus, bands 1, 3 and 7 were present, but bands 2, 5, 6 and 8 were absent in few. Some individuals of Wesafu were found to possess weaker bands 3 and 7. The band frequency between samples studied indicated serum protein  polymorphism, which indicated genetic diversity between ‘Wesafu’ and O. niloticus

Hybridization and speciation among cichlids: the case of 'Wesafu', an ecotype cichlid

Fishes of the family Cichlidae are known for spectacular adaptive radiation and therefore serve as a model for evolutionary and ecological studies. They are highly speciated due to hybridization that frequently occur in the wild. The existence of an ecotype cichlid, ’wesafu’ in Epe Lagoon, Lagos, Nigeria appears to be the result of such hybridization. This paper reviews the profile of wesafu and compare the species with other cichlids, evaluate the probable causes of speciation which includes diversity in feeding morphology, mate choice, adaptation to changes in habitat arising from water level dynamics , eco-phenotypic variation, restricted migration to predation and introgressive hybridization. The implication of such speciation and hybridization were also highlighted

Comparative study of proximate composition of some wild tilapiine fishes in Epe Lagoon, Lagos, Nigeria

The proximate composition of some wild tilapiine fishes in Epe lagoon, Lagos, Nigeria was analyzed. The species were Sarotherodon melanotheron, Tilapia guineensis, Tilapia mariaei, Sarotherodon galileaus and an ecotype cichlid popularly called ‘wesafu’. Major nutrient compositions of raw muscles like protein, fat, moisture and ash were determined. Proximate compositions were found to be varied among the species. Protein was determined in Sarotherodon melanotheron (19.13%), T. guineensis (18.71%), T. mariae (18.08%), S. galileaus (18.34%) and ‘wesafu’ (21.80%) respectively. Lipid content was recorded as 0.82%, 0.40%, 0.60%, 0.65%, and 0.90% for the tilapia species. The highest level of moisture content was found in T. guineensis (81.70%) and the lowest was in ‘wesafu’ (78.50%). The percentage of ash content was highest in S. galileaus and S.melanotheron (1.75%) and lowest in T. guineensis (1.00%). The present study revealed highest protein content in the ecotype cichlid, wesafu (19.22%) and lowest value in T.mariae (18.08%) while fat was highest in ‘wesafu’ (0.90%). The results of this study reveal the nutritional significance of the ecotype cichlid, ‘wesafu’ above other cichlids of the lagoon

Growth performance of wild strains of Clarias gariepinus from Nigerian waters

The catfish (Clarias gariepinus) is the leading aquatic crop in Nigeria. Most of the strains used in aquaculture are suffering from in-breeding depression with its attendant poor egg and sperm quality. There is therefore the need to explore the natural population of the fish to improve performance. This study was carried out to evaluate the growth performance of strains of the catfish across the fresh water systems of Nigeria. Collections were made from the six geopolitical zones namely: North-Central (Kogi), Northeast (Adamawa), Northwest (Kebbi), South-West (Oyo), Southeast (Anambra), South-South (Delta) and domesticated strain obtained from Lagos. The fish were bred in the wet laboratory of the Department of Fish Technology/Biotechnology of the Institute for Oceanography and Marine Research, Lagos and fed for 12 weeks before subjected to growth study. The study involved allocation of 25 juveniles of each strain in lm hapas installed in a 0.4 ha at Badore fish farm, Lagos, Nigeria,fed 3% body weight twice daily while sampling forth-nightly. The results showed that the domesticated strain of C. gariepinus performed significantly better (a=0.05) than the six wild strains studied. This may be attributable to selective breeding which probably had been carried out by the farmers from which the broodstocks were purchased and mixture of the gene pool of improved Dutch strain commonly cultured. There was however no significant variation in the SGR and FCR among the strain. However, the growth study showed that the strain from North-West (Kebbi) did not perform as much as other strains in terms of these growth indices. Hoewever, it had the highest survival (96%). The strains from Oyo and Anambra however showed better growth over the rest strains from the wild. The implication of the breeding potentials of C. geriepinus strains from Kebbi, Oyo and Anambra is that if several selective breeding of these strains are carried out and the gene pool of Kebhi is combined with any of these two, we are likely to obtain fish seed of better growth and survival