<b>Efficacy of eugenol extracted from the plant <em>Eugenia aromatica</em> as an anesthetic for the biometry procedures in Nile tilapia (<em>Oreochromis niloticus</em>) adults</b> - doi: 10.4025/actascianimsci.v32i4.9973

Abstract

Anesthetics represent a powerful tool in aquaculture, working to reduce stress and mortality commonly caused by handling. The objective this work was evaluate the effect of various concentrations of eugenol in adults of Nile tilapia and determine its optimal concentration for biometry procedures. Six concentrations (30, 60, 120, 180, 240 e 300 mg L^-1) were tested. For each treatment, 12 fishes (average length: 32.7 ± 3.0; average weight: 557.0 ± 160 g) were individually immersed in anesthetic solution for 10 min. All stages of anesthesia were monitored during anesthetic induction, and upon profound anesthesia the opercular beat rate was monitored for the next minute. After anesthetic induction, the fishes were transferred to an aquarium containing water without anesthetic solution, and recovery time was measured. The 60 mg L^-1 concentration required more time to reach the desired stage of profound anesthesia (206.3 seconds), while the 300 g L^-1 concentration reached this stage more rapidly (77.8 seconds). Results suggest that the optimal concentration of eugenol for biometry procedures is 120 mg L^-1, and that increase anesthetic dosage results in reduced opercular beat rate.