The present study was aimed at determining the effects of taurine and/or methionine addition to a plant-based diet on growth performance and immunological and antioxidant responses of Persian sturgeon, Acipenser persicus. Four plant-based diets were formulated, including control (C), control+1 g/kg taurine (T), control+2 g/kg methionine (M), and control+1 g/kg taurine and 2 g/kg methionine (T+M). Fish were fed each diet in triplicate for 70 days, and growth performance, hematological, plasma biochemical, and immunological parameters, and hepatic and erythrocyte antioxidant parameters were determined after that. Dietary taurine or methionine supplementation significantly increased growth performance, hematological parameters, antioxidant enzymes' activities, plasma lysozyme, alternative complement, and total immunoglobulin but decreased plasma alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase activities, and malondialdehyde. Interaction additive effects of dietary taurine and methionine were observed in erythrocyte count, hematocrit, alternative complement, total immunoglobulin, hepatic malondialdehyde, superoxide dismutase, and glutathione peroxidase. In conclusion, dietary taurine (1 g/kg) and methionine (2 g/kg) supplementation is necessary to support higher growth rate, immunological responses, and antioxidant capacity in Persian sturgeon, when fed a plant-based diet. According to the present results, the highest performance is obtained when both amino acids are simultaneously added to the fish diet.