An 8-week growth trial was conducted to evaluate the effects of a plant protein blend (PPB, comprised of soybean meal and wheat gluten meal) as fishmeal (FM) substitute on growth, nitrogen (N) and phosphorus (P) balance in Siberian sturgeon, Acipenser baerii Brandt. Two control diets were formulated to contain two protein levels (400 and 360 g kg−1). At each protein level, FM was totally replaced by PPB with supplement of crystalline essential amino acids and mono-calcium phosphate. Growth performance was not affected by dietary protein sources and protein levels. Fish fed the low-protein diets had higher FI than that of the high protein groups, while fish fed the FM-based diets had higher FI than that of fish fed the PPB-based diets. N/P intake of fish showed linear relationship with total N/P loss. The productive P value was significantly affected by dietary protein sources, but no significant effects were shown on productive N value. The results suggest that Siberian sturgeon fed total plant-based diets with balance of EAA could maintain normal growth performance and reduce total P excretion both at 360 and 400 g kg−1 protein levels.