Abstract:The effects of four socking densities [G1 (100 ind./m3), G2 (200 ind./m3), G3 (300 ind./m3), and G4 (400 ind./m3)] on the growth indices, energy metabolism content, and metabolic enzyme activity of Fenneropenaeus chinensis were studied in a 28-day indoor culture experiment via the cage culture method. The results showed that the weight gain rate, relative growth rate, and specific growth rate of the G2 group were highest and did not differ from G1 (P>0.05). The weight difference coefficient of G3 and G4 increased significantly (P<0.05). The weight gain rate, relative growth rate, specific growth rate, and survival rate were significantly lower than G1 (P<0.05), and the G4 group differed significantly from the G1 group (P<0.01). The G3 and G4 groups significantly increased the levels of hemolymph glucose, lactic acid, and pyruvate (P<0.05) and reduced the triglycerides content (P<0.05). The glucose, lactic acid, pyruvate, and triglyceride contents of G2 did not differ from G1 (P>0.05). The amino acid content also did not vary between densities (P>0.05). This indicates that high-density stress can increase energy demands, and F. chinensis tend to use sugars and lipids as energy sources when experiencing density stress. The activities of hexokinase, pyruvate kinase, 6-phosphate fructokinase, and lactate dehydrogenase in G3 and G4 were significantly increased (P<0.05), suggesting changes in the body's oxidative metabolism pathways and increased catabolism. Succinate dehydrogenation enzyme activity was significantly reduced (P<0.05), indicating a decrease in tricarboxylic acid cycle activity. This provides further evidence that density stress inhibited aerobic metabolism. In summary, growth in the G3 and G4 groups was significantly affected, there was increased use of carbohydrates and lipids, and aerobic metabolism of the tissues was inhibited in F. chinensis. Therefore, 100~200 ind./m3 is recommended as the appropriate density when F. chinensis are 4.5 g.