Effects of anesthetic eugenol on respiration and excretion of Sinogastromyzon szechuanensis

In order to select a more suitable anesthetic for the breeding and transportation of Sinogastromyzon szechuanensis, we used different concentrations of anesthetic eugenol (0, 6,12,18,24,30 mg•L⁻¹) to test the effects of the respiratory and metabolic on Sinogastromyzon szechuanensis with an average mass of (2.029±0.26) g under the water temperature (18±0.5) °C. Based on regression analysis method, the regression equations of oxygen consumption rate, ammonia removal rate and temperature were calculated. (R²> 0.99). Oxygen consumption rate and ammonia removal rate were calculated and compared by One-Way ANOVA (Turkey method) using SPSS 25.0 software. The multiple comparison results revealed that when the mass concentration of eugenol reached 24 mg•L⁻¹, it could significantly reduce the oxygen consumption rate and ammonia excretion rate (p<0.05). With the increase of eugenol concentration, the oxygen consumption rate and ammonia excretion rate of the Sinogastromyzon szechuanensis first increased and then decreased. Under the influence of eugenol, the oxygen consumption rate and ammonia excretion rate of Sinogastromyzon szechuanensis were increased with the increase of temperature (p<0.01). When the water temperature is 14-26°C, the oxygen-nitrogen ratio is 8.0-19.4, and the temperature is positively correlated with the oxygen-nitrogen ratio. It is concluded that eugenol with a mass concentration of 24 mg•L⁻¹ can make Sinogastromyzon szechuanensis enter the stage of anaesthesia II (sedation), so this concentration is recommended as the anesthetic dosage for transportation, and the anesthetic effect at low temperature is more obvious.