This study was conducted to assess optimal salinity level among 0‰, 5‰, 10‰, 15‰, 20‰ and 25‰ for successful breeding of Nile tilapia, Oreochromis niloticus. The duration of study was 56 days. Brooders (48) having mean weight (male 162±0.2 g and female 160±2.5 g) were selected and stocked into hapa nets in 12 fiberglass tanks (2000-liter). Ratio among male and female was 1:3. They were fed with commercial floating pelleted feed constituting 35% crude protein with 2% body weight twice a day. Eggs were collected on weekly basis by cultch removal method. Results showed that the highest fecundity, fertility, hatchability and survival of fry were obtained on salinity of 0%-15% and significantly decreased on 20‰ and 25‰. The eggs per gram body weight were also recorded in all treatments and highest eggs were obtained i.e. 4.0-4.3 per female on 0‰-15‰. Water temperature (28.02±0.12°C), dissolved oxygen (6.4±0.02 mg/L), pH (7.47±0.04) and ammonia (less than 0.022±0.001 mg/L) were monitored throughout the study period. Water quality parameters remained within the recommended range. Our results suggest that Nile tilapia, O. niloticus may give maximum eggs up to 15‰ salinity with 92% survival of fry.