Tropicultura (Jan 2005)
Essais d'adaptation de production massive de juvéniles de Clarias gariepinus en conditions rurales
Abstract
Adaptive Trials for Intensive Clarias gariepinus fingerling to Rural Conditions. Artificial reproduction and fingerling production of the African catfish Clarias gariepinus (Burchell 1822) have been tested under less controlled conditions to adapt the intensive technology used by Aquafarm (Tihange, Belgium) to rural conditions present in developing countries. The main aim was to compare the efficiency of ovaprim a synthesised hormone with catfish pituitary extracts. Fecundity and quality of eggs (egg weight) were not significantly different. Incubation results on water hyacinth and on mosquito mesh frames were compared to those obtained in Zoug jars; the latter showed a higher hatching rate (67%) than water hyacinth (39%) and mosquito mesh frames (44%). Larvae were stocked at different stocking rates in ponds (T1: 800 larvae.m-3 and T2: 1600 larvae. m-3 ) and in tanks (T3: 3200 larvae.m-3 et T4: 6400 larvae.m-3). After a 50-day nursing period, no significant difference (P> 0.05) was observed for specific growth rate (SGR) and survival rate, but better SGR were observed in ponds (18.34%.d-1) than in tanks (16.81%.d-1). In general, production was slightly higher in tanks than in ponds being related to a higher stocking density. Significantly higher harvests were obtained from tanks with higher stocking densities but the sizes of the larvae were very heterogeneous. In such case, it is recommended to grade the larvae at 6 or 7 days intervals using different mesh sizes (from 3 to 5 mm). These less intensive rearing conditions gave nevertheless good fingerling productions.
