Abstract: Juvenile fat greenling Hexagrammos otakii with body weight of(83.3±7.8)g was anaesthetized by clove oil at a dose of 10， 20， 30， 40， 60， 80， 100 and 110 mg/L and by MS－222 at a doses of 10， 20， 30， 40， 50，60 and 70 mg/L and by natural sea water as control and the respiratory rate was determined at water temperature of(15±0.5)℃ in the juveniles exposed to the clove oil and MS－222 at the doses， above to highlight the anesthetic effect of clove oil and MS－222 on fat greenling.The recovery time was determined in the fat greenling juveniles first exposed to the clove oil and MS－222 at a dose of 80 mg/L for 5 min and then exposed to air for 0， 3， 4， 5， 6， 7，8 and 9 min.The anesthesia process is divided into 6 periods，and recovery process is classified into 4 periods depending on the behavioral characteristics of the fish.The results showed that the fat greenling became into anesthesia within 3 min and recovered within 5 min at clove oil concentration of 50－100 mg/L and MS－222 concentration of 50－70 mg/L.A few fish died of shock and less than 100%of recovery rate were observed in the fish exposed to clove oil concentration of over 100 mg/L and MS－222 concentration of 70 mg/L for 15 min anesthesia.The fish anaesthetized by clove oil had low respiratory frequency， while the fish anaesthetized by MS－222 showed significantly accelerated breathing in the phase 4，with only small amplitude stretching posterior to operculum.The recovery time under deep anesthesia was found to be longer with time extension of air exposure，with the safe air exposure of 7 min in the anesthetic effect of clove oil， and the safe air exposure of 5 min in the anesthetic effect of MS－222.The findings indicate that clove oil and MS－222 as good anesthetics for fat greenling are characterized by short anesthesia time and quick recovery.
2017, Vol. 32 
