Abstract: The anesthetic effects of various concentrations （10, 20, 30, 40, and 50 g/L） of Urethane on adult crucian carp Carassius auratus with body weight of 230 g±9.46 g were studied by bath at room temperature （ 15-25 ℃ ） to provide the practical anesthesia parameters. The results showed that the anesthesia time was reduced with the concentration increase and the recovery time was lengthened （P〈0.05） at concentration of 10-50 g/L, without significant difference compared to 40 g/L （P〉0.05）. Within the concentration of 10-40 g/L, the fish in all groups had 100% of recovery, whereas the fish in the 50 g/L group had 88% of recovery rate. Within the concentration of 10-50 g/L, the fish in all groups had 100% of survival rate in 7 days, indicating that the anesthetic safety concentration was 40 g/L. The multi-comparison showed a significant relationship between concentration and drug bath time in bounce time on the crucian carp in air except the two concentration group （50 g/L and 40 g/L）. There were no significant differences between the drug bath time in all groups （10 min and 5 min）, and the drug bath time at 10 g/L for 25 min and 20 min （ P〉0.05 ）. The Urethane was found to have the valid anesthetic effects on crucian carp in a short time in acute experiments, and used as a kind of effective fish anesthetic.
2011, Vol. 26 
