Some Biological Observations on Rearing Juveniles of Nile Tilapia (Oreochromis niloticus (Linnaeus, 1758)) in Fixed Cages at Gezira Irrigation Canals, Sudan

This study was conducted at Gezira Irrigation canal to evaluate the growth performance and the effect of water tempetrature to the culture ability of Nile tilapia juveniles for 120 days. Monosex Oreochromis niloticus sized 8.17±0.33 g were carried out from Mabroka fish farm and stocked in 400 m³ fixed cages at a density of 50 fish/m³. Fish were fed daily with a commercial pellet diet with 33% protein concentration at a feeding rate of 3% of their body weight per day. Feed was given twice a day (09:00 morning and 16:00 evening). Fish growth parameters, water quality analysis have measured every two weeks. The final body weight of fish was 40.23±1.04 grams and the mean daily gained weight was 0.29 g/day, while the survival rate of fish was 99.7%±6.7 and the Food Conversion Ratio (FCR) was 3.8. The average value of temperature, pH and transparency were 23°C, 7.5, 31.5 cm respectively. The results of the study revealed that there is a possibility to culture tilapia juvenile at stocking density of 50/m³ in fixed cages in Irrigation Canals, for the effect of water temperature on fish growth performance the results obtained that no more effect on fish growth during study period.