Comparison of Electroanesthesia with Chemical Anesthesia (MS222 and Clove Oil) in Rainbow Trout (Oncorhynchus mykiss) using Plasma Cortisol and Glucose Responses as Physiological Stress Indicators

This study investigates Alternating Current (AC) electroanesthesia of rainbow trout (Oncorhynchus mykiss) in comparison with MS222 and clove oil, using plasma cortisol and glucose concentrations as stress assessment indicators. A microcontroller-based apparatus was designed and constructed to allow a programmable voltage-time Pulse-Width Modulated (PWM) electrical wave application through 19x20 cm submersible electrodes for 91sec in a 33 cm long tank to induce loss of equilibrium and immobility with recovery after 52+/-27 sec. Recovery after 660+/-102 sec was observed in MS222-anesthetized fish (after induction for 720+/-72 sec) and a recovery time of 546+/-102 sec was observed in clove oil-anesthetized fish (after induction for 144+/-42 see) both are significantly longer recovery times in comparison with electroanesthesia (p<0.001). Using direct enzyme-linked immunosorbant assay (ELISA) for cortisol and enzymatic colorimetric assay for glucose assessments at 0, 1, 6, 12 h after each anesthesia, the anesthetics indicated similar trend of cortisol responses during 12 h of investigation. The dilatory trend of glucose changes and response derived from anesthetics and electricity and its surge at 6 h after anesthesia (p<0.05) confirmed glucose as a second order indicator of stress responses. Electroanesthesia is a fast, economic, eco-friendly and safe anesthetic method provides desirable trout immobility for aquaculture activities.