Supplementation of Sage (Salvia officinalis) Essential Oil in Balanced Diets for Tropical Gar (Atractosteus tropicus) Larvae on Digestive and Antioxidant Enzyme Activities and Expression of Immune System Genes

The tropical gar (Atractosteus tropicus) has significant ecological, economic, and cultural importance in southeast Mexico, where aquaculture is increasing and fish are frequently exposed to stress. In this sense, feed additives such as sage (Salvia officinalis) strengthen organisms’ growth, immune systems, antioxidant capacities, and digestive capabilities. A 30-day experiment was conducted on larvae to determine the effect of different concentrations of sage essential oil (0%, 0.5%, 1%, 1.5%, and 2% treatments) supplemented in balanced diets. Significant differences (p < 0.05) between 0.5% and 2% sage oil supplement treatments for average weight were found. The highest acid and alkaline proteases, chymotrypsin, leucine aminopeptidase, amylase, and lipase activities were obtained for the sage oil-supplemented treatments. In contrast, trypsin showed the highest activity for treatment 0%, followed by diets with 0.5% and 2% sage oil. Regarding the antioxidant enzymatic activity for GPx, CAT and SOD, the highest activity was obtained in the diet with 1% sage oil, while in PEROx, the highest activity was recorded in the treatment with 0%, 1.5% and 2% S. officinalis supplementation. On the other hand, for relative gene expression, the highest expression was observed in sage-supplemented treatments for the nod, zo-1, zo-2, and occ genes. In contrast, the lowest expression was found in supplemented treatments for the il-10 and muc2 genes. These findings suggest that incorporating sage essential oil into the diets of tropical gar larvae, particularly at concentrations of 1.66% and 1.77%, holds potential for enhancing aquaculture practices for this important species.