Effect of season on controlled propagation of the African catfish, clarias gariepinus (Burchell 1822).

Abstract

The effect of season on the controlled propagation of C. gariepinus was investigated. The hypophysation of C. gariepinus using the pituitary extract from the sacrificed C. gariepinus was carried out from July, 1987 to June 1988. The female broodstock weight ranged from 0.50kg while the male weight, from 0.5kg to 0.6kg. The condition factor of the female broodfish was more or less uniform (1.3 to 1.7). The results showed that there was peak production of eggs by the female during the rainy season. Eggs production for rainy season ranged from 28,000 eggs/kg body weight in June to 37,600 eggs/kg body weight in August. The percentage hatching of the fertilized eggs was also higher in the rainy season than the dry season. The highest hatching of the fertilized eggs of 86.4% was obtained in July and the lowest of 40.1% in December at the temperature range of 23oC to 27oC respectively. The hatching of the fertilized eggs occurred between 23 to 29oC with the optimum at 27oC. The hatching of the eggs took place from 18 to 30 hours. The fry were stocked into 1000m2 grow –out ponds 4 days after hatching. The fry were reared to fingerlings in the grow-out pond for four weeks. Fingerlings percentage survival from the fry was within the range of 13.6% to 54.0%. The highest fry survival of 54.0% was obtained in September and the least of 13.6% in January. This study has shown that controlled propagation of C.gariepinus can be done year round.