Abstract: To explore the effects of long period of MS-222 anesthesia on juvenile large yellow croaker (Larimichthyscrocea), juvenile large yellow croaker with body weight of (97.97±9.56) g were exposed to different MS-222 concentrations of 10, 20, 30, 40, 50, 60 and 70 mg/L in glass fiber reinforced plastic bucket at water temperature of (16±1)℃ for 24 h. Histological and electron microscopic structures were observed in the liver, and gill filament and antioxidant enzyme (superoxide dismutase SOD, catalase CAT, and glutathione oxidase GSH-Px) activities in live and serum cortisol level in the anesthetic large yellow croaker exposed to the different concentrations of MS-222. The results showed that the juveniles turned into the deep sedation period in anesthesia process at MS-222 concentration of 40 mg/L and into the deep anesthesia period at the concentration from 60 mg/L to 70 mg/L. However, the large yellow croaker juveniles had recovery rate of only 50% 24 hours after 70 mg/L anesthesia. The histological section and electron microscope observation showed that liver, gill and pituitary were slightly damaged by 40 mg/L anesthesia for 24 h. The antioxidant enzyme activity and serum cortisol level were found to be significantly increased at 20 mg/L MS-222 at 1.5 h (P<0.05), with an overall enhancement effect on activities of SOD, CAT, and GSH-Px at 20 and 40 mg/L MS-222 anesthesia. There was basic similarity in activities of SOD, CAT and GSH-Px between group 20 mg/L and group 40 mg/L 6 h after recovery in clean water. To sum up, according to the determination of anesthetic concentration of MS-222 on juvenile large yellow croaker and the study on MS-222 influence on the body, it is speculated that the concentration of 40 mg/L is the basis for long-term transportation.
2023, Vol. 38 
