Abstract: In order to provide reference data for the disease control in Chinese perch (Lateolabrax maculatus) culture, this paper studied the acute toxicity of different concentration trichlorfon to the perch fry and juvenile. The GSH and MDA concentrations and SOD, CAT, GOT, GPT, and AChE activities in juvenile liver were determined, and the total dyskaryosis and micronuclear rates of juvenile erythrocytes were calculated. The LC₅₀ for the perch fry exposed to trichlorfon was 7.76 mg·L^-1 (24 h), 3.02 mg·L^-1 (48 h), 1.74 mg·L^-1 (72 h) and 1.58 mg·L^-1 (96 h), and the safe concentration was 0.14 mg·L^-1; while the LC₅₀ for the perch juvenile exposed to trichlorfon was 10.96 mg·L^-1 (24 h), 6.15 mg·L^-1 (48 h), 3.98 mg·L^-1 (72 h) and 2.89 mg·L^-1 (96 h), and the safe concentration was 0.58 mg·L^-1. Lytic necrosis was observed in the liver tissues of agonal individuals. After exposed to trichlorfon for 48 h, and with the increase of trichlorfon concentration, the juvenile liver’s GSH concentration decreased first, then recovered, and decreased again, MDA concentration increased first and recovered then, SOD activity had no significant difference with that of the control group, CAT activity decreased first and recovered then, GPT activity maintained at lower level, GOT activity of 1.35 and 2.70 mg·L^-1  trichlorfon groups decreased, and AChE activity had a slight increase after an initial decrease. The GSH and MDA concentrations and the CAT, GPT、GOT and AChE activities were sensitive, while the SOD activity was not sensitive to the trichlorfon stress. After exposed to 1.45 mg·L^-1 and 0.73 mg·L^-1 of trichlorfon for 96 h, the juvenile’s total erythrocyte dyskaryosis rate and micronuclear rate were significantly (P<0.05) higher than those of the control group respectively.

Key words: Temperature effectiveness, Methanogen, Methanotroph