Effects of Two Anesthetics on Survival of Juvenile <i>Culter mongolicus</i> during a Simulated Transport Experiment

Abstract

Abstract Cultivation of the redtail culter Culter mongolicus has been increasing substantially over the last decade along the Yangtze River basin; such increases in production lead to increased juvenile transportation. However, redtail culter juveniles have high transport mortality rates due to a strong stress response that is exacerbated by the accumulation of toxic metabolic waste. Through a 24-h simulated transport experiment (sampling every 6 h), we assessed effects of tricaine methanesulfonate (MS-222) at 10 mg/L of water, 20 mg/L, and 40 mg/L on redtail culter survival and water quality parameters, and similarly we assessed clove oil at 2 mg/L of water, 5 mg/L, and 10 mg/L. None of the anesthetics significantly improved water quality during the initial 6–12 h of the experiment. However, MS-222 treatments at the first 12–24 h of the experiment had significantly higher dissolved oxygen (DO), ammonia, and pH than the control but failed to decrease un-ionized ammonia content. In contrast, the clove oil treatment significantly reduced the un-ionized ammonia but failed to improve DO and pH at 12–24 h. The improvements in water quality were reflected in cumulative mortality, MS-222 and clove oil anesthetic treatments having significantly lower cumulative mortality than the control at 12–24 h. The MS-222 and clove oil slowed water quality deterioration, ensured a better transport environment, and improved juvenile survival during transportation. We recommend 5 mg/L clove oil be used when transporting juvenile redtail culters because that concentration improves fish survival while keeping cost low.