In attempts to improve aquaculture performances, the examination of environmental factors affecting the healthy growth and nutritional profile of fish have been of great interest over the years. This study evaluated the effects of salinity on the growth, survival, proximate and fatty acid compositions of juvenile Nile tilapia (Oreochromis niloticus, 5.93 ± 0.51 g). Using commercial diets, salinity treatments of 9, 18 and 27 ppt (Experiment I) and 5, 10 and 15 ppt (Experiment II) were applied, with 0 ppt (freshwater) serving as the control for both experiments. In both of two rearing experiments, the highest weight gain was obtained in the control group (0 ppt) followed by 5 ppt group in Experiment II, while the higher salinity groups exhibited lower weight gains. Regarding final survival, a mass mortality was observed in the highest salinity group (27 ppt), whereas other groups achieved high survival rates of 83.0-93.3% in Experiment I and 97.0-100.0% in Experient II. The nutritional profile results from both trials strongly indicate an inverse relationship between salinity and the protein and lipid contents of the fish body. Both experiments demonstrated similar trends, showing that the fish reared in 0 ppt exhibited higher contents of highly unsaturated fatty acids, which are crucial dietary components for both of finfish and humans. Overall, results suggest that a salinity range of 0 ppt to 5 ppt is optimum for achieving good growth, survival, high nutritional quality, and fair palatability in juvenile Nile tilapia.

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