Growth performance and body composition of Nile Tilapia (Oreochromis niloticus) reared at different water salinities.

Abstract

The present study evaluated the growth performance and body composition of Oreochromis niloticus reared at different water salinities (0 %0, 6 %0, 12 %0 and 18 %0¬). The experiment lasted for 70 days through which the fish were fed a standard diet (40 % protein) twice daily of about 3 % of fish body weight. The water temperature was maintain at 29  0.5 °C. The final weight , total weight gain, daily growth rate and specific growth rate of fish were varied significantly (p<0.05) at different water salinities and decreased with the increase of salinity. The total protein content of fish didn't show a significant difference (p>0.05) in their content except at water salinity of 12 and 18%0 where the values recorded of fish flesh was decreased significantly. On the other hand, throughout the tested periods, fish showed irregular patterns in their contents of fat, moisture and ash. The water salinity did not affect (p>0.05) the gross energy (GE) content of fish except at water salinities 12 and 18 %0 where GE was decreased significantly. Finally it should be borne in mind that Oreochromis niloticus can tolerate the water salinities up to 18 %0 but the upper threshold of the optimum salinity for optimum growth is 6 %.