To investigate the anesthetic and sedative effects of eugenol on juvenile Eleutheronema tetradactylum, as well as its effects on gill tissue damage and liver antioxidant capacity in juvenile fish, five different concentrations of eugenol (5, 10, 15, 20, 25 mg·L-1) were used to anesthetize juvenile fish with an average total length of (6±0.324) cm and average body weight of (1.6±0.336) g at (30 and 35) ℃, the concentration of eugenol was further refined according to its behavior in eugenol. The experimental results show that: under the conditions of (30 and 35) ℃, 1) with the increase of eugenol concentration, the time of juvenile entering the same period of anesthesia was significantly decreased (P＜0.05); 2) the optimal anesthetic concentration of eugenol for juvenile was 0.1 mg·L-1, 3) the activities of liver antioxidant enzymes (SOD, CAT, GPX and T-AOC) were significantly increased in different concentrations of eugenol (P＜0.05); 4) with the increase of eugenol concentration, gills were damaged. When eugenol concentration was 0.1 mg·L-1, the gills of juvenile fish were slightly damaged at the 6th hour, but the damage was alleviated after the 12th hour.[Chinese Fishery Quality and Standards, 2024,14(4):01-13]