This research was carried out to determine that the effects of diets containing 30% hazelnut meal and different proportions of phytase enzymes on the growth performance of Siberian sturgeon (Acipenser baerii) (initial mean weight, 960.23 ± 0.55 g). The trial diets consisted of feeds supplemented with 0.25 g kg-1 (G2), 0.50 g kg-1 (G3), and 1.00 g kg-1 (G4) phytase enzyme, and with no enzyme added to the control group (G1), respectively. Experiment groups were performed in 3 replicates and trials were carried out for 90 days. As a result, adding phytase enzyme to feeds contain 30% hazelnut meal was found to have a positive effect on the weight gain (WG, g), the protein efficiency ratio (PER), feed conversion ratio (FCR), and specific growth rate (SGR, %). Growth performance was found to be more successful in all groups fed feeds supplemented with phytase enzyme compared to the G1 group (P<0.05). The G4 was the best group than the others statistically (P<0.05). In terms of the digestibility effect of enzyme added groups, the highest total digestion rate (77.14 ± 0.07%) was obtained in the G4 enzyme group and the lowest total digestibility (74.32 ± 0.02%) was estimated in the G1.