Enhancing anesthesia and minimizing toxicity: evaluation of clove, Cinnamon, and tea tree essential oils in nile tilapia (Oreochromis niloticus)

This study evaluates the anesthetic effectiveness and potential reduction of toxicity in Nile tilapia (Oreochromis niloticus) through the use of clove, cinnamon, and tea tree essential oils. We evaluated genetic damage, enzymatic activity, and gene expression. We conducted two experiments. In experiment 1, we individually evaluated the anesthetic efficiency and genotoxicity of these essential oils. In experiment 2, we assessed their combined effects at different concentrations. Clove oil, particularly at the highest concentration (200 µL/L), induced genotoxic effects and oxidative stress in fish, leading to alterations in gene expression regulation and enzymatic activity. Tea tree and cinnamon oils, at concentrations of 75 and 100 µL/L, required longer times to induce fish to the anesthesia stage and were less efficient in achieving deep anesthesia stage. Notably, combining tea tree and cinnamon essential oils to clove oil showed promise as an alternative to using clove oil alone. This combination demonstrated potential as an effective anesthetic and may help mitigate the genotoxic effects associated with clove essential oil. Our findings suggest a viable option to minimize potential physiological damage during the anesthesia process in aquaculture, thereby promoting a balance between this necessary procedure and animal welfare.