Use of eugenol for the anaesthesia and transportation of freshwater angelfish (Pterophyllum scalare)

Abstract

This study aimed to evaluate the effectiveness of eugenol for the induction and anaesthesia recovery of freshwater angelfish juveniles, and to verify its effectiveness for transportation. Juveniles were exposed to different concentrations of eugenol: 0 (control), 10, 15, 20, 30, 40, 50 and 60 μL L−1 (equivalent to 10.6, 15.9, 21.2, 31.8, 42.4, 53.0 or 63.6 mg L−1). Afterwards, other fish were divided into two groups: sedated with 15.9 mg L−1 eugenol and non-sedated, and they were evaluated 4 and 7 h after transportation. The minimum effective concentration for sedation and anaesthesia occurred with 15.9 and 53.0 mg L−1 eugenol, respectively. The total ammonia was significantly higher in the control group than the sedated group 7 h after transportation. Blood glucose levels were significantly higher in the sedated fish in relation to the control group 7 h after transportation. The gill histopathology analysis and muscle glycogen levels were not influenced by eugenol or the time of transportation. It is concluded that 15.9 and 53.0 mg L−1 eugenol were effective concentrations for sedation and anaesthesia in juveniles, and that 15.9 mg L−1 eugenol has the potential to be used for the transportation of freshwater angelfish for up to 7 h.