Routine measures of stress are reduced in mature channel catfish during and after AQUI-S anesthesia and recovery

Mature channel catfish Ictalurus punctatus were exposed to water containing three different concentrations (20, 40, and 60 mg/L) of AQUI-S (50% isoeugenol) during routine handling procedures at a commercial catfish facility. Anesthetic efficacy, recovery time, and the effects of AQUI-S on routine measures of stress were compared with similar measures in a group of fish sampled prior to anesthesia (preanesthesia [PA] group) and a group anesthetized with 100 mg tricaine methanesulfonate (TMS)/L. On average, all the fish lost equilibrium at 8.0, 3.9, and 3.7 min when anesthetized in 20, 40, and 60 mg AQUI-S/L, respectively. Fish anesthetized with TMS lost equilibrium at 4.5 min. Recovery time in freshwater was 2.1, 2.8, and 5.3 min for fish anesthetized in 20, 40, and 60 m,-/L AQUI-S, respectively. Recovery time after TMS anesthesia was 1.7 min. Short-term (24-h) survival was 100% for all treatments, and long-term (21-d) survival ranged from 87.5% for TMS-anesthetized fish to 98.8% for fish anesthetized in 40 mg/L AQUI-S. All anesthetic treatments significantly reduced (P < 0.05) plasma cortisol levels relative to PA fish, and circulating cortisol was lower (P < 0.05) in all AQUI-S-anesthetized fish than in TMS-anesthetized fish. Plasma glucose concentrations were significantly lower (P < 0.05) in fish anesthetized with 40 mg/L AQUI-S than in PA and TMS-treated fish after both anesthetization and recovery. Plasma lactate and chloride concentrations were not reduced (P > 0.05) in any treatment compared with the levels in PA fish. Fish anesthetized with 40 mg/L AQUI-S had lower (P < 0.05) plasma lactate levels after recovery than TMS-anesthetized fish, and plasma chloride levels were significantly lower (P < 0.05) immediately following AQUI-S anesthesia at all concentrations than in fish anesthetized with TMS. Anesthesia did not affect (P > 0.05) postrecovery plasma chloride concentrations. Overall, AQUI-S exhibited efficacy as an anesthetic for mature channel catfish and demonstrated stress-reducing properties during handling procedures.