Fish cage culture allows intensive production in waterbodies without conventional preparation for aquaculture.Considering the importance and prospects of cage culture in Bangladesh, the present experiment was undertaken to study the effect of stocking density on growth performances and production potential of tilapia (Oreochromisniloticus) under cage culture conditions and to develop a suitable method of tilapia cage culture in inland open water body like Old Brahmaputra River. Three stocking densities (100, 150 and 200 fish m-3) of 2.78 g mean initial individual body weight of fingerlings in three different treatments (T-100, T-150 and T-200) each with three replicates were used. The fishes were supplied with high protein (30%) commercial feed at 10% of body weight twice daily. Water quality parameters namely transparency, temperature, pH, dissolved oxygen, phosphate were found within the suitable limit for fish culture.The result of the present study showed that the fish in the treatment T-150 resulted the best individual weight gain (90.72g), average daily gains (0.67 g), percent weight gains (3263%), specific growth rates (1.13%day-1) and the net production rates (13608gm-3135 days-1)followed by treatments T-100 and T-200, respectively.The net yield and growth performances showed a significant difference with increasing stocking density (P<0.01). The most effective stocking density was150 fish m−3 cage for Nile tilapia considering growth performances and production potential. Therefore, it can be concluded the growth performance of Nile tilapia is density dependent.