Author(s): MOHAMED SAAD ELSHERIF
Nile tilapia (Oreochromis niloticus) fingerlings averaging 19.0±1.0 g in weight were stocked for 60 days, at different levels of pH (6, 7, 8 & 9) using 12 glass aquaria (40×70×60 cm). Tilapia were fed with diet containing 26.58% crude protein. Water was changed twice daily with 100% of water size. Growth measurement of tilapia was recorded at 15 days intervals. Blood parameters were recorded at stocking and at the end of the experiment. Results showed that growth performance was significantly (P≤0.05) decreased at pH 6 and 9, while the differences between pH 7 and 8 were not significant (P≥0.05). No mortality occurred during the whole experiment. Feed conversion ratio (FCR) increased at pH 6 and 9, since its value at the pH 6 was significantly (P≤0.05) higher than pH 9. Decreasing pH resulted in decreased hematocrit and hemoglobin values, while differences were not significant (P≥0.05) from control in pH 7, 8 and 9. It was concluded that water pH 7-8 could be more suitable to tilapia culture for optimum growth performance and survival rate.