Evaluation of Gambusia, Gambusia affinis, Fish Meal in Practical Diets for Fry Nile Tilapia, Oreochromis niloticus

This study was conducted to evaluate the use of gambusia, Gambusia affinis, fish meal (GFM) in practical diets for fry Nile tilapia, Oreochromis niloticus (2.11 ± 0.11 g). Six isonitrogenous diets (35%) were formulated in which GFM replaced 0.0, 10, 25, 50, 75, or 100% of the protein supplied by herring fish meal (HFM). Fish were fed one of the test diets at a feeding rate of 4% of the fish body weight 6 d a week, 2 times a day for 13 wk. Results demonstrated that fish growth increased with increasing GFM up to 75%, which produced the highest growth of the treatments. The lowest fish growth was obtained at 100% GFM. Feed intake (FI), protein efficiency ratio (PER), and apparent protein utilization (APU) increased significantly, while feed conversion ratio (FCR) decreased significantly with increasing GFM up to 75%. FI, PER, and APU decreased significantly, while FCR increased significantly for diets containing 100% GFM. There were no significant differences in moisture, protein, lipid, or ash contents in final fish body following inclusion of GFM in fish diet. There was no significant difference in the digestibility coefficient of dry matter. The digestibility coefficients of protein and gross energy for diets containing 100% GFM replacement were the lowest as compared with other GFM levels. The present study recommended that GFM is a suitable protein source in practical diets for fry Nile tilapia and could replace HFM up to 75%.