Effects of anesthetic MS-222 and eugenol on oxygen consumption rate and ammonia excretion rate of Sinogastromyzon szechuanensis

In order to improve the survival rate of Sinogastromyzon szechuanensis in the processes of production, breeding and transportation, we measured the anaesthetic effects of MS-222 and eugenol at different mass concentrations on S. szechuanensis with body mass of (2.029±0.26) g at water temperature of (18±0.5) ℃ by the method of closed respirometry, and explored the effects of MS-222 and eugenol on the oxygen consumption rate, ammonia excretion rate and oxygen nitrogen ratio (O/N). The results show that when the mass concentrations of MS-222 and eugenol reached 1.5 mg·L⁻¹ and 24 mg·L⁻¹, respectively, the oxygen consumption rate and ammonia excretion rate decreased significantly (P<0.05). With the increase of mass concentration of MS-222, the oxygen consumption rate and ammonia excretion rate continued to decrease. With the increase of mass concentration of eugenol, the oxygen consumption rate and ammonia excretion rate first increased and then decreased. Under the stress of two kinds of anesthetics, the oxygen consumption rate, ammonia excretion rate and O/N increased with increasing water temperature at water temperature of 14–26 ℃. When O/N was 8.0−19.4, there was very significant difference in oxygen consumption rate and ammonia excretion rate between different temperature groups  (P<0.01). In conclusion, MS-222 at 1.5 mg·L⁻¹ or eugenol at 24 mg·L⁻¹can make S. szechuanensis enter the stage of Anaesthesia II (sedation), which can be recommended as the anesthetic dosage for the transportation of live fish, and low temperature is appropriate.