Evaluation of a Portable Electrosedation System for Anesthetizing Mature Channel Catfish

Abstract

Hybrid catfish (female Channel Catfish Ictalurus punctatus × male Blue Catfish I. furcatus) fry are produced by hormone-induced spawning of Channel Catfish in hatcheries. Anesthetics are used routinely to reduce handling stress by limiting the activation of the hypothalamic–pituitary–interrenal axis hormones. As a comparison, the present study determined the efficacy of electrosedation using a portable electrosedation system (PES) and its feasibility for possible application in hybrid catfish hatcheries. The PES was evaluated at 100 V and a 25% duty cycle at 30, 60, 90, or 100 Hz to anesthetize mature Channel Catfish to stage IV of sedation. The PES was compared to the chemical sedatives tricaine methanesulfonate (MS-222; 200 mg/L) and metomidate hydrochloride (Aquacalm; 6 mg/L). The PES at 30 Hz anesthetized Channel Catfish in 4 s, significantly faster than the 120 s needed for MS-222. However, the mean (±SE) time to recover from anesthesia and mean plasma cortisol response were similar (P > 0.05) with MS-222 (104 ± 9 s; 35 ng/mL) and the PES (119 ± 15 s; 32 ng/mL). Relative fecundity of fish sedated by the PES and MS-222 averaged 5,222 and 5,593 eggs/kg of body weight (BW), respectively; percent hatch averaged 46.9% and 50.4%, respectively; and hybrid catfish fry production averaged 1,644 and 1,711 fry/kg BW, respectively. Relative fecundity, percent hatch, and hybrid fry production were not significantly different between the PES and MS-222 groups (P > 0.05). No internal injuries were noted in any of the fish subjected to electrosedation. The PES at 30 Hz effectively anesthetized female Channel Catfish with a quicker induction time, provided moderate time to recover from anesthesia, and elicited a cortisol response, with no known internal injuries. The results suggest that the PES has the potential to replace MS-222 usage in hybrid catfish hatcheries. The PES is environmentally safe, does not expire or degrade, and requires no disposal or withdrawal period.