EFFECT OF FEEDING DIFFERENT DIETARY PROTEIN LEVELS ON REPRODUCTIVE BIOLOGY OF AFRICAN MUD CATFISH (Clarias gariepinus)

摘要

A feeding trial was conducted to evaluate effects of feeding different dietary protein levels on reproductive biology of African mud catfish under hapa system. Catfish fingerlings (mean body weight (4.50± O.Olg) and total length (8.0±0.2cm) were randomly stocked at 20 fish per hapa (lm3). Five experimental diets with crude protein (CP): 50.00%, 47.50%, 45.00%, 42.50% and 40% were fed in three replicates to the fish at 5% of their body weight. Gonad development of 260-day old catfish was investigated histological and morphologically. Results revealed that fish fed 50% CP diets had significantly higher (P < 0.05) milt volume, milt density, sperm motility, ova diameter and proximate composition, and oocyte developmental stage than those fed all otherdiets. Coefficient of maturity and gonad somatic index increased with protein content of diet while hepatic and visceral somatic indices were proportional to fish body weight. Test of significance for the relationships between fecundity/total length, fecundity/body weight and fecundity/gonad weight indicated that the values of correlation coefficient (R2) were highly correlated; R2 > 0.9 at P < 0.05 for fish fed 50% and 45% protein diets. This may mean that high protein diets (45% - 50%) favoured catfish gonads' maturity. Therefore, the relationships: fecundity/total length; fecundity/body weight and fecundity/gonad weight alongside other gonad maturity indices were important in fisheries management for comparative growth studies.