African catfish Clarias gariepinus (Burchell, 1882) constitutes a bulk of farmed freshwater fish, particularly in Africa. Its optimal production relies on an optimal feeding regime as feed covers about 50% of operation cost. Studies on feeding regimes have mostly been on feeding frequency and the daily required rations. This study was therefore designed to evaluate the impact of varied proportions of normal daily rations on the performance of C. gariepinus juveniles. Clarias gariepinus Juveniles of 17.6 ± 3.7 g were stocked at a density of 15 juveniles per 50 L of water in 80 L plastic tanks and cultured indoors for 42 days. They were fed a standard specific feed at 5% total biomass three times daily (8:00, 13:00 and 18:00). Treatment 1 received 33.33% of its daily ration at each feeding period, while treatments 2 and 3 received (50%, 25% and 25%) and (25%, 25% and 50%) of the daily rations at 8:00, 13:00 and 18:00, respectively. Fish biomass and survival rate were determined weekly and individual fish weights and lengths were determined at the end of the experiment. Water was aerated continuously and half the volume was renewed daily; temperature and pH were monitored twice daily. The specific growth rate, weight and length gained were best in treatment 3 although not significantly different (p>0.05) among treatments. However, feed conversion ratio and condition factor in treatment 3 were significantly (p<0.05) better when compared to treatments 1 and 2 although temperature and pH in the different treatments were not significantly different (p>0.05). The estimated investment cost was 3891, 4136 and 3907 FCFA, with profit index of 0.95, 0.87 and 1.09 in treatments 1, 2 and 3, respectively. Therefore, administering about 50% of the daily ration in the evening as was the case in treatment 3 is more profitable in the culture of C. gariepinus juveniles.
In Cameroon, wild strains of Clarias gariepinus (Burchell, 1822) are often used for artificial reproduction in hatchery facilities, but there is insufficient information on their reproductive capacity and progeny performance. The reproductive capacity of two strains of C. gariepinus from the Mezam and Mungo Rivers and the performance of their F1 larvae obtained following hybridization were assessed. Reproduction was carried out with four crosses as follows: Mezam (♂) x Mezam (♀) (T1), Mezam (♂) x Mungo (♀) (T2), Mungo (♂) x Mezam (♀) (T3) and Mungo (♂) x Mungo (♀) (T4). Thereafter, three days old larvae obtained following reproduction were subjected to a 30 day experimental trial with standard feeds. The performance of larvae obtained from T4 was not assessed since larvae obtained were too few for the experiment. Although the broodstock of the different strains did not differ significantly in size, Mezam stock had significantly (p = 0.00) bigger eggs when compared to Mungo stock. Fecundity of 52480 was recorded for Mezam stock compared to 32985 for Mungo stock. Fertilization and hatchability rates differed significantly (p < 0.05) among the crosses, with the highest (82.28 and 81.31%, respectively) in T1, followed by T3 (65.96 and 61.28%, respectively), and the least (38.61 and 2.81%, respectively) in T4. The best larval survival was recorded in T1 (37.17%) and the least in T2 (15.67%), meanwhile T3 recorded best growth after 30 days. In terms of fertilization and hatchability, T1 was more suitable for artificial reproduction, but T3 is more encouraged for aquaculture based on its reproductive capacity and larval performance.
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