Effects of Anesthetic Disposal on the Physiological and Behavioral Responses of the Lined Seahorses, Hippocampus erectus

Anesthetic disposal for fish often results in physiological and behavioral responses. There is limited information involved on the metabolic and behavioral responses of the seahorses. The lined seahorse, Hippocampus erectus, is of great interest in the sciences because of its unusual S‐shaped morphology and male pregnancy behavior. This study found that the lined seahorse could be effectively anesthetized into Stage II at the concentrations of 10 mg/L clove oil or 20 mg/L MS‐222 based on the comparison of six different treatments. The ventilation frequency, oxygen consumption, and ammonia‐N excretion of the seahorses were decreased significantly as soon as they were exposed to the anesthetic agents. A higher O : N ratio was found in seahorses anesthetized by clove oil as compared to those exposed to MS‐222. After the anesthetic treatment, the feeding frequencies of recovered seahorses were low at the beginning and then increased during the 7‐d culture. Moreover, there was no incremental difference of wet weights among the tested seahorses (P = 0.534). The findings indicate that the anesthetic process has few effects on the feeding and short‐term growth of seahorses in spite of the occurrence of physiological and behavioral responses.