Optimum dietary protein requirement of three-spotted tilapia (Oreochromis andersonii, Castelnau, 1861) juveniles reared under suboptimal temperature conditions

Abstract

Abstract The optimization of the nutritional requirements of native tilapia species is vital for enhancing aquaculture productivity and promoting sustainable fish farming in sub-Saharan Africa. This study evaluated the optimum dietary protein requirement of the three-spotted tilapia ( Oreochromis andersonii , Castelnau, 1861) juveniles reared under suboptimal mean temperature conditions (19.28 ± 0.10 °C). A total of 225 fish (initial mean weight 2.51 ± 0.19 g) were randomly assigned to five diets containing 34%, 36%, 38%, 40%, and 42% crude protein, with three replicates per treatment. After 8 weeks, fish fed the 38% protein diet achieved significantly higher final body weight (FBW), weight gain (WG), and specific growth rate (SGR), with a lower feed conversion ratio (FCR), compared to the 34% group. Survival rate (SR) and condition factor (K) were unaffected by protein level. Whole-body composition analysis showed higher crude protein content in fish fed the 42% diet, while crude fat decreased with increasing protein levels; ash content peaked in fish fed the 38% diet. Second-order polynomial regression estimated the optimum dietary protein requirement at 38.3% (FCR-based) and 38.5% (SGR-based) at a 95% confidence level. These findings suggest that a dietary protein level of approximately 38% promotes optimal growth and feed efficiency in O. andersonii juveniles reared under suboptimal mean temperature (~ 19 °C) conditions. This study provides essential guidance for practical feed formulation and supports the expansion of sustainable aquaculture systems in the region.