GPT and infection: This study revealed a characteristic dynamic pattern in the hemolymph ALT and AST activities of red claw crayfish following A. veronii infection, exhibiting an increase peaking at 24 h post-infection followed by gradual decline until returning to baseline levels by 96 h, reflecting the typical physiological stress response of crustaceans to pathogenic challenge where early-stage infection (24 h) induces hepatopancreatic tissue damage leading to elevated ALT/AST activities, while subsequent immunological activation (48–96 h) progressively mitigates tissue damage [32].