Rearing of African catfish (Clarias gariepinus) and vundu catfish (Heterobranchus longifilis) in traditional fish ponds (whedos): Effect of stocking density on growth, production and body composition

African catfish (Clarias gariepinus) (initial body weight: 34.8 ± 4.8 g) and vundu catfish (Heterobranchus longifilis) (initial body weight: 39.1 ± 8.2 g) fingerlings were stocked at densities of 4, 6 or 8 fish m in traditional fish ponds (whedos) constructed in the floodplain of the Oueme River (South Benin, West Africa), for 70 days from March to June 2005. Fish were fed twice a day with 34% crude protein feed formulated with locally available ingredients. The effects of stocking density were evaluated in growth responses, gross production and body composition. Water quality variables were similar (p > 0.05) in all compartments. Temperature and pH were at the optimum level for fish. Dissolved oxygen ranged from 0.9 to 1.2 mg l during the experiment and secchi disc transparency was low (<14 cm). In both species, growth responses increased with the increasing density, significantly in African catfish stocked at density of 8 fish m compared to the other densities (4 and 6 fish m) but not significantly in vundu catfish. Production data ranged from 3.1 ± 0.5 to 22.8 ± 4.5 t ha year in African catfish and from 6.1 ± 1.2 to 15.1 ± 3.1 t ha year in vundu catfish. Production increased with increasing stocking densities but only significantly (p <0.05) between the density of 8 fish m and the other densities. In both species, carcass fat increased with increasing density (p <0.05) while carcass protein and moisture decreased (p > 0.05). These results are important because they indicate that, as far as growth rate and production are concerned, African catfish is more profitable than vundu catfish for culture at high density in whedo.