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The probiotic effects of Saccharomyces cerevisiae and Aspergillus niger on the feeding efficiency, body composition, ammonia excretion, blood serum enzymes and the intestinal microbiota of juvenile beluga, Huso huso was investigated. The fish (31.8±2.81g) were randomly allocated into 12 oval tanks at a density of 30 individuals per tank with three replicates for each treatment,. The fish were fed either a basal diet (as control) or the diet supplemented with S. cerevisiae and A. niger (2×10⁶, 4×10⁶ and 6×10⁶ cells g^-1) for 8 weeks. The results indicated that the probiotic supplemented diet at 6×10⁶ (cells g^-1) significantly improved FCR and other nutritional indicators compared to the control treatment (p<0.05). Significant improvements (p<0.05) were also observed in ammonia excretion and blood serum enzymes between treatments. Total viable fungus and Lactobacillus spp. count were significantly improved in treatment compared to control (p<0.05). These results indicated that S. cerevisiae and A. niger improved feeding performance and blood serum enzymes of beluga.