Stocking density is an important factor affecting aquaculture water quality and fish growth performance. Recirculating aquaculture test and nitrate nitrogen acute treatment test of Takifugu rubripes were conducted to investigate the effects of stocking density (12.5–20.0 kg /m3) and nitrate nitrogen mass concentration (1.0, 25.0, 100.0 and 150.0 mg/L) on aquaculture water quality, growth performance, stress response and antioxidant status of Takifugu rubripes. The results indicated that the stocking density had no significant effect on pH, ammonia nitrogen and nitrite nitrogen mass concentration in the aquaculture water of Takifugu rubripes, but higher density would lead to significant increase in nitrate nitrogen mass concentration, with the maximum value being 24.5 mg/L. Higher stocking density resulted in lower growth performance (final weight, specific growth rate and bait conversion rate) and antioxidant capacity (total antioxidant capacity, superoxide dismutase and glutathione peroxidase) and higher lipid peroxidation (MDA) and stress response (glucose, lactic acid and cortisol). In addition, in nitrate nitrogen acute treatment test, no Takifugu rubripes died. When the nitrate nitrogen mass concentration was 100.0 and 150 mg/L, the antioxidant capacity of Takifugu rubripes was lower while the stress response was higher. In conclusion, when the stock density was 16.5 kg/m3, the growth and antioxidant status of Takifugu rubripes were good and the stress response was lower, which indicated that under higher density, the increase of nitrate nitrogen mass concentration in aquaculture water was not the main reason for fish growth inhibition.