Assessment of induction and recovery times of anaesthesia in <i>Astyanax bimaculatus</i> using 2‐phenoxyethanol and the essential oils of <i>Melaleuca alternifolia</i> and <i>Ocimum gratissimum</i>

Abstract

This study aimed to determine the lowest effective concentration (LEC) of 2-phenoxyethanol (2-Phe) and essential oils (EOs) of Melaleuca alternifolia and Ocimum gratissimum able to induce anaesthesia in Astyanax bimaculatus. LEC was assumed to be the required concentration to carry out anaesthesia in less than 3 min with recovery in <5 min and sufficient to carry out routine aquaculture procedures. The following concentrations were tested: 2-Phe (100, 200, 300, 400, 500 and 600 µl/L); M. alternifolia (200, 300, 400, 500 and 600 µl/L); and O. gratissimum (10, 20, 30, 40, 50, 60, 70, 100, 150, 250 and 300 µl/L). Results show that all three agents evaluated have effective anaesthetic properties for use in Astyanax bimaculatus with LEC for 2-Phe, M. alternifolia and O. gratissimum of 200, 300 and 60 µl/L respectively.