Ocimum basilicum essential oil as an anesthetic for tambaqui Colossoma macropomum: Hematological, biochemical, non-specific immune parameters and energy metabolism

Abstract

The present study evaluated the efficacy of Ocimum basilicum (basil) essential oil in the anesthetic induction and recovery of juvenile tambaqui Colossoma macropomum and verified its physiometabolic effects after biometric handling. Juveniles (86.51 ± 7.82 g) were exposed to different concentrations of basil essential oil: 400, 500, 600, 700, 800, 900, and 1000 μL L−1. Subsequently, the fish were divided into five groups: control (non-handled fish), handling without anesthetic (water only), handling with ethanol (720 μL L−1), and handling with Ocimum basilicum essential oil (400 and 800 μL L−1). The shortest (p < 0.05) time to induce anesthesia was at a concentration of 1000 μL L−1 (222 s). The recovery time from anesthesia did not differ significantly among different concentrations (400–1000 μL L−1). The results of the present study confirm the essential oil of O. basilicum as a new and safe natural anesthetic for juvenile tambaqui. The use of this essential oil in biometrics handling procedures reduces or attenuates the secondary responses to handling stress without showing deleterious effects on the non-specific immune system or metabolism of energy, carbohydrates, and lipids. However, further studies are necessary to determine the exact mechanism of action of this essential oil.