Taurine is one of the most studied amino acids in aquaculture over the last decade. This study was conducted to investigate the taurine requirements in terms of growth, immune system, antioxidant enzyme activities and stress response of beluga (Huso huso) (209.1 ± 23 g) in both fresh water (FW) and brackish water (BW: 15 ppt). Twelve experimental tanks with six taurine levels (2.1 g/kg_21.8 g/kg), for FW (Tau2.1, Tau4.3, Tau7.1, Tau12.3, Tau16.7 and Tau21.8) and BW (BwTau2.1, BwTau4.3, BwTau7.1, BwTau12.3, BwTau16.7, and BwTau21.8), were designed to feed and farm fish for eight weeks. Generally, fish farmed in BW had better growth and immune response performance compared with FW. The quadratic relations for pooled data determined taurine requirements in terms of weight gain (12.1 g/kg), lysozyme (13.5 g/kg), IgM (12.7 g/kg) and osmolality (15.1 g/kg) (p<0.05). Furthermore, taurine requirements to obtain the minimum cortisol before and after stress were 10.4 g/kg and 14.3 g/ kg, respectively. When we exposed fish to high stock density stress (12 kg/m 3 for 4 hours), those fed dietary 16.7 and 21.8 g/kg had more stable glucose, cortisol and lactate before and after stress in both FW and BW. In conclusion, beluga fed diets with 12.3 g/kg and 16.7 g/kg taurine in both FW and BW groups had the best performance regarding growth and health status, respectively.