Use of eugenol as an anaesthetic for Geophagus brasiliensis juveniles

Abstract

The eugenol is the active ingredient of clove oil and it has shown to be effective and safe as fish anesthetic. In this study the effects of different concentrations of eugenol for anesthesia, recovery time, blood glucose and hematocrit percentage of pearl cichlid (Geophagus brasiliensis) juveniles were evaluated. Concentrations of 50, 80, 100, 120, 150, 170 and 200 mg L^-1 eugenol were evaluated in terms of time to achieve the different stages of anesthesia and recovery in a completely randomized design (CRD) with 12 repetitions. These results were tested using the Kruskal-Wallis test with subsequent Dunn test. The evaluated concentrations had anesthetic action of the deep induction 172.57 ± 25 s (50 mg L^-1) and the period of full recovery of 516.25 ± 102 s (200 mg L^-1), with statistical difference between the treatments at all the stages. The eugenol effect on blood glucose and on hematocrit percentage at 0 h after deep anesthesia was evaluated for concentrations of 0; 50; 80; 100; 150 and 200 mg L^-1 in a completely randomized design with five replications, and the results were assessed by One-Way ANOVA. Glucose and percentage of hematocrit: no statistically significant differences (P>0.05) were observed for these variables. All concentrations of eugenol showed to be effective as an anesthetic for G. brasiliensis and did not affect the survival, blood glucose and the percentage of hematocrit. To minimize adverse effects and achieve faster recovery, it is indicated the use of 50-80 mg L^-1 of eugenol for pearl cichlid juveniles.