RESUMEN
The dietary composition of fish constitutes numerous immune and growth-promoting substance; during the current study, methionine was amended in the diet of Labeo rohita (L. rohita), in order to appraise the diverse modulatory effects of methionine supplementation. Fish were grouped into three on the basis of methionine as methionine supplemented group 1 (MSG1), methionine supplemented group 2 (MSG2), and CTRL (control group). We assessed the effects of methionine at the end. Captivating results were obtained from the methionine supplementing groups. The results depict significantly high (p < 0.05) innate immunity parameters, including myeloperoxidase, IgG concentrations, lysozyme, respiratory burst, and total bacteriolytic activity of complement in MSG2. Furthermore, ameliorate growth performances were also noticed such as high weight gain, FCE%, and body length in MSG2, respectively. We also measured high level of antioxidant digestive enzymes, gut length, and survival rate in MSG2 compared to the rest of the groups. The results were further validated by measuring the stress parameters, such as aspartate aminotransferase (AST), glucose, and hematocrit (HCT%), and the concentration remains low in MSG2. Lastly, after 90 days, fish were challenged with Aeromonas hydrophila, the highest survival was observed in the MSG2 and MSG1 compared to CTRL. These results ultimately give the baseline to the credible effects of methionine on L. rohita.