This study assessed the effects of stocking density (D02, 0.2 individuals/m2; D03. 0.3 individuals/m2; D04, 0.4 individuals/m2; D05, 0.5 individuals/m2; D06, 0.6 individuals/m2) on Chinese mitten crab (Eriocheir sinensis; 6.25?±?0.11 g) growth performance, tissue indices, antioxidant enzyme activity (total superoxide, catalase, glutathione peroxidase, total antioxidant capacity, and malondialdehyde), and mRNA expression of antioxidant-related genes (SOD, CAT, GPx) in rice crab culture systems. Our results demonstrated that increasing stocking densities decreased the final weight (FBW), weight gain rate (WGR), specific growth rate (SGR), feed conversion efficiency (FCR), and protein efficiency ratio (PER) of the crabs. The hepatosomatic index (HSI) of female crabs in D04 group was higher than that of other groups. The gonadosomatic index (GSI) of the male crabs in the D04 group was significantly higher than that of the other groups(P?<?0.05). The meat yield (MY), total edible yield (TEY), and condition factor (CF) of the female and male crabs in the D04 group were higher than those of the other groups. The antioxidant enzyme activity (T-SOD, CAT, GSH-Px, and T-AOC) of male and female crabs in the D04 group was significantly higher than that of the other groups, and the MDA content of the D04 group was significantly lower than that of the other groups (P?<?0.05). The stocking density of 0.4 individuals/m2 effectively promoted the efficient mRNA expression of SOD, CAT, and GPx genes in the hepatopancreas of male and female crabs. In summary, the optimal stocking density of E. sinensis in the rice crab culture system is 0.4 individuals/m2.
