Response of African Catfish, Clarias gariepinus, to Different Dietary Protein and Lipid Levels in Practical Diets

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Abstract This study was conducted to find the optimum level of dietary protein and lipid that could produce the highest growth, best feed utilization, and body composition of African catfish, Clarias gariepinus (9.5–10.3 g). Nine diets (three protein levels × three lipid levels) containing 25, 30, or 35% crude protein (CP) with 6, 9, and 12% lipids were formulated. Fish were fed one of the tested diets at the rate of 5% of body weight for the first 8 wk and 3% for the rest of the study. Diets were offered 6 d a week, twice a day (900 and 1400 h) for 13 wk. Fish growth increased significantly with increasing either protein or lipid levels, and the maximum growth was obtained in fish fed diets containing 30% CP with 12% lipid or 35% CP with 9% lipid. The lowest fish growth was obtained at 25% CP with 6% lipid. The optimum feed intake, feed conversion ratio, energy utilization, protein efficiency ratio, and protein growth rate were also recognized in fish fed the above diets. No significant differences in moisture and ash contents in fish fed diets containing different protein and lipid levels were recorded. The protein and lipid contents in the fish body tended to increase with increasing protein and lipid levels in diets. However, the higher protein contents were obtained in fish fed diets containing 35% CP with 6 or 9% lipid, while the lowest ones were obtained at 25% CP with 6 or 9% lipid. The higher lipid contents were obtained at 30 or 35% CP with 12% lipid, while the lowest ones were obtained at 25 or 35% CP with 6% lipid. The present study indicates that the increase of dietary lipid level has a protein‐sparing effect, and the diet containing 30% CP with 12% lipid would be suitable for the optimum growth and effective protein utilization of fingerling African catfish.