Increasing groundwater scarcity and salinity pose challenges for high water demand aquaculture. Adapting animals to grow optimally under saline conditions is key to future growth in many important aquaculture regions. In the current study, 10-week controlled feeding experiment was carried out to investigate dietary sodium chloride supplementation (10% NaCl) as a method of mitigating the effects of increasing water salinity (0,10 and 15 ppt) on growth and metabolism of juvenile Nile tilapia, Oreochromis niloticus in controlled feeding experiments. Fish fed diets supplemented with 10% NaCl recorded significantly better weight gain when compared to fish fed control when held in 10  and 15 ppt salinity water over a period of ten weeks. Blood glucose and blood lactate concentrations were both significantly higher in fish fed diets supplemented with 10% NaCl and increased with increasing water salinity. Fish fed diet containing 10% NaCl recorded the highest values of Na⁺ concentration in blood compared to other experimental groups. Feed utilization, as indicated by feed conversion ratio decreased significantly with water salinity (P < 0.05). Feed intake also decreased with increasing water salinity. The obtained results indicated that salinity is a key factor in controlling the growth of Nile tilapia. Results clearly indicate that negative effects of increased salinity in rearing water can be partially mitigated by salt inclusion in diets.