en aquaculture aquaculture پژوهشي Orginal research papers This study assessed the effects of diets supplemented with canola protein hydrolysate (CPH) on growth performance, blood biochemistry, immunity, and gastrointestinal microbiota of beluga (<em>Huso</em> <em>huso</em>) juveniles. CPH concentrations of 0, 300, 400, and 500 mg kg^-1 diet were denoted as control, CPH₃₀₀, CPH₄₀₀, and CPH₅₀₀, respectively and were added to fish basal diet. 840 beluga juveniles (30&plusmn;6 g) were assigned into the four dietary treatments and fed for 56 days. The diet supplemented with 500 mg kg^-1 of CPH significantly decreased food conversion ratio (FCR). Condition factor (CF), specific growth rate (SGR), body weight gain (BWI), standard length (SL), total length (TL), survival rate, and food consumption demonstrated a CPH dose-dependent increase, with highest values in the fish treated with CPH₅₀₀. Concentrations of blood (serum) cholesterol, triglyceride, and glucose decreased in a CPH-concentration dependent manner as well. Red blood cells (RBC) and white blood cells (WBC) increased and decreased, respectively in all fish treated with CHP, especially in CPH₅₀₀ treatment. Moreover, gastrointestinal population of <em>Lactobacillus</em> spp. and total bacteria were significantly enhanced in the treated groups, with the highest loads of total bacterial (2.1&times;10⁶CFU) and <em>Lactobacillus</em> spp. (1.6&times;10⁴ CFU) in CPH₅₀₀ treatment. Taken together, CPH could be introduced as an alternative for fishmeal in beluga diet, although more studies are needed to be conducted to elucidate the underlying mechanisms by which CPH improves fish growth. Bacterial population, Canola, Growth performance, Hydrolyzed protein 1165 1178 http://jifro.ir/browse.php?a_code=A-10-3979-1&slc_lang=en&sid=1 M.R. Ebrahimnezhadarabi mahmoudreza2020@gmail.com 100319475328460041065 100319475328460041065 No Department of Aquaculture, Babol branch, Islamic Azad University, Babol, Iran R. Changizi changizi@baboliau.ac.ir 100319475328460041066 100319475328460041066 Yes Department of Aquaculture, Babol branch, Islamic Azad University, Babol, Iran S.M. Hoseinifard sm_hosseinifard@yahoo.com 100319475328460041067 100319475328460041067 No Department of Veterinary, Babol branch, Islamic Azad University, Babol, Iran S. Vatandoust s.vatandoust@gmail.com 100319475328460041068 100319475328460041068 No Department of Aquaculture, Babol branch, Islamic Azad University, Babol, Iran S. Ghobadi shgh_science@yahoo.com 100319475328460041069 100319475328460041069 No Department of Aquaculture, Babol branch, Islamic Azad University, Babol, Iran