Asian Journal of Fisheries and Aquatic Research

The study was conducted to investigate the frequency of water change on the growth performance, nutrient utilization and body indices of Oreochromis niloticus juveniles. O. niloticus of average body weight of 15 g were stocked and fed with 42% crude protein diet twice daily. The experiment had three treatments with 50% changing of water, every 2days, every 4days and every 7days. The water quality parameters were not significantly different among the treatments except for pH. Weight gain, percentage weight gain and specific growth rate were slightly higher in the 4days interval of changing water with values; 57.65±8.95 g, 33.93±5.16 % and 0.52±0.07 % day^-1 respectively. Higher but not significant yield in relation to the volume of water used was obtained in 7days interval (0.46±0.09 Kg m^-3). Slightly higher values of condition factor, viscerosomatic index and hepatosomatic index were recorded in the 4days water changing interval. Higher glycogen content was observed in water changes every 4days. All the livers were healthy with the mildest vacuolations in the treatment with water changes once in a week. The results showed that O. niloticus juveniles can be reared with water changes every 7days with no negative consequences. Water changes every 4days tended towards the best.