Benzocaine, MS-222, eugenol and menthol as anesthetics for juvenile Mugil liza

Abstract

Anesthesia has been used as an aquaculture technique to facilitate the manipulation of the animals and to alleviate the stress caused by the management procedures. The present study aimed to determine the anesthetic efficacy of four drugs in Mugil liza juveniles. Fish (6.9 ± 1.4 g) were individually anesthetized (N=10 by concentration) using four concentrations of benzocaine (30, 40, 50 and 60 mg L^-1), MS-222 (100, 125, 150 and 175 mg L^-1), eugenol (50, 70, 90 and 110 mg L^-1) and menthol (175, 200, 225 and 250 mg L^-1). The criterion used to evaluate the best concentrations was the maximum time interval of 3 and 5 minutes for anesthesia and recovery of the fish respectively. The most efficient concentrations were: benzocaine, 50 mg L^-1; MS-222, 150 mg L^-1; eugenol 70 mg L^-1 and menthol 225 mg L^-1.