The optimum level of dietary protein and feeding for improving the growth performance and feed efficiency of juveniles Hybrid tilapia (Oreochromis niloticus× Oreochromis aurea) reared in brackish water

A 6-weeks factorial trial (2 × 2) was conducted to determine the optimum level of dietary protein and the optimum feeding rate for the best growth and feed efficiency of hybrid tilapia, Oreochromis niloticus × Oreochromis aurea. Two dietary protein levels were examined; 27% and 34% CP with 5% and 7% of the biomass, and each treatment was performed in triplicate. Twelve plastic tanks (54 × 38 × 28 cm: L × W × H) were used to accomplish this work. The average initial weight was determined (7.5 ± 0.16 g), and fish samples were stocked (12 juveniles/tank).  Fishes were fed three times daily and 6 days weekly. The water was daily exchanged at a rate of about 20% of water volume/tank. Results showed that dietary protein levels (from 27% to 34%) did not significantly affect either growth or feed usage parameters. However, 7% feeding rate had significantly higher growth parameters than 5%. Statistical analysis of the interaction between dietary protein and feeding levels showed that fishes fed at 7% as the feeding level with dietary protein at 27% or 34% was significantly higher in growth than those fed at 5% with the same diets. Additionally, results confirmed the significant difference in specific growth rate and survival rate of fishes fed at 7% as feeding rate with any diet protein level. Thus, this study suggests that 27% CP with 7% as feeding rate is more for the best growth of hybrid tilapia juvenile under the same conditions of this trial.