An experiment was conducted to compare effect of stocking density on growth performance of monosex tilapia (Oreochromis niloticus) with Indian spinach (Basella alba) in a recirculating aquaponic system. The experiment was set-up for 8 weeks under 4 treatments with three replications, where stocking density of tilapia were 30, 50, 70 and 90 fish/tank (300 litre) in treatments T1, T2, T3 and T4, respectively. Water from the tank was recirculated through a vegetable growing tray. Each of the tray was 0.15 m3in size, which was planted with 12 plants (Indian spinach). The fish of all the treatments was fed two times a day. During the experimental period,the range of water temperature was 27.1 to 31.50 C, pH 7.48 to 8.28, ammonia 0.2 to 2.0 mg/l and dissolve oxygen 5.11 to 6.58 mg/l. At the end of the experiment, average weight gain, final length, specific growth rate (%/day), survival rate was significantly higher in T1 (30 fish/tank) treatment while the net yield of fish and plant biomass was higher in T2 (50 fish/tank) treatment.Therefore, the study suggests that stocking density of 50 fish/tank for tilapia, i.e. 167 fish/m3, is suitable for production of both plant and fish in a recirculating aquaponic system.