Eugenol as an anesthetic for two African cichlid species (Aulonocara nyassae and Aulonocara stuartgranti): effects on induction time, recovery time and ventilatory frequency

Abstract

This study evaluated the anesthetic efficacy of eugenol for two size classes of Aulonocara nyassae and Aulonocara stuartgranti. The experimental groups were classified as follows: A. nyassae, Juvenile I-Any (1.29 ± 0.35 g) and Juvenile II-Any (2.97 ± 0.67 g); and A. stuartgranti, Juvenile I-Ast (1.98 ± 0.60 g) and Juvenile II-Ast (3.69 ± 0.74 g). For each group, 80 specimens were randomly allocated to seven eugenol concentrations (25, 50, 75, 100, 125, 150 and 175 mg L-1) and a control (ethanol) in a completely randomized design with 10 individuals per concentration. Anesthesia trials involved exposing one animal at a time to the different eugenol concentrations, and recording induction time, recovery time, but ventilatory frequency was also measured during induction and recovery. The efficacy of an anesthetic administered via immersion bath is related to rapid induction to deep anesthesia (<180 s) and short recovery (<300 s). Therefore, the study demonstrated that eugenol concentrations between 50 and 175 mg L-1 are recommended for Juvenile I-Any and between 25 and 175 mg L-1 for Juvenile II-Any. The ideal concentrations for A. stuartgranti, on the other hand, range from 25 to 175 mg L-1 for both evaluated size classes.