Experiments were conducted to determine the activities of protease and carbohydrase in growing lensky sturgeon fed with three different diets containing various concentrations of protein and carbohydrate. Neutral pretense activity from growing lensky sturgeon the protein diet (predo-minary, almost $100\%$ protein) was lower then those from fish fed the other diets during the experimental period. The results may indicate that the level of pretense activity is inversely related to the level of protein in the diets.