Two experiments were conducted to evaluate effects of using soybean meal to replace fish meal in practical diets for feeding of juvenile crayfish (Pacifastacus leniusculus). In experiment 1, four practical diets containing 35, 40, 45 or 50% crude protein were fed to crayfish. Results indicated no significant differences in survival rates between treatments and crayfish weight gains plateau at 45% crude protein. In experiment 2, four practical diets (50% crude protein content) were prepared to test replacement levels of FM protein by SBM protein of 0% (control group), 25%, 35% or 45%, in crayfish diets. Replacement levels of 0% and 25% SBM enabled the highest crayfish survival and growth. The research team concluded that feeding a supplement with 45–50% dietary protein with soybean meal replacing 25% of the fish meal protein can be recommended for juvenile P. leniusculus during the first period of intensive rearing.