fa پژوهشي Orginal research papers An 8-week feeding trial was conducted to evaluate the effects of dietary commercial prebiotic A-Max, a mixture of mannan oligosaccharides, fructo oligosaccharides and &beta; glucan, on growth and hemato-immunological parameters of great sturgeon (<em>Huso huso</em>) juveniles. After acclimation, fish (initial weight of 28.79&plusmn;0.85 g) were placed into 12 tanks (30 fish per tank). Fish were fed a basal diet (containing 44% protein and 20% lipid) supplemented with 0 (control), 0.5, 1.0 and 1.5 g kg^-1 A-Max in a totally randomized design in triplicate groups. At the end of the trial, growth factors and haemato-immunological parameters were assessed. Fish fed 1.5 g kg^-1 prebiotic mixture displayed higher growth performances and feed efficiency compared to the control group (<em>p</em>>0.05). There were no significant differences in survival rate among all treatment groups (<em>p</em>>0.05). The results showed that RBC, WBC, lymphocyte, neutrophil, haematocrit and total protein were significantly affected by 1.5 g kg^-1 dietary prebiotic mixture (<em>p</em><0.05). An elevation of monocyte and haemoglobin (<em>p</em>>0.05) was found in the fish fed diet containing 1.0 g kg^-1 prebiotic. In addition fish fed the diet with 1.5 g kg^-1 prebiotic mixture showed a significant increase in lyzosyme activity, respiratory burst activity, serum total immunoglobulin (Ig) and alternative complement activity (ACH50) (<em>p</em><0.05) compared with those fed the diets supplemented with other levels of prebiotics. The results showed that the addition of 1.5 g kg^-1 prebiotic mixture to the diet of great sturgeon juveniles improving growth performance, some haematological parameters and immune response and seemed to be an effective immunostimulant.&nbsp; &nbsp; &nbsp; Prebiotic mixture, Growth, Hematology, Immune response, Great sturgeon (Huso huso) 251 266 http://jifro.ir/browse.php?a_code=A-10-1181-3&slc_lang=fa&sid=1 R. Akrami akrami.aqua@gmail.com 100319475328460029463 100319475328460029463 Yes Department of Fisheries, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran. Department of Fisheries, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran. H. Chitsaz 100319475328460029464 100319475328460029464 No Department of Fisheries, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran. Department of Fisheries, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran. F. Lakzaei 100319475328460029465 100319475328460029465 No Iranian Fisheries Sciences Research Institute,Tehran,Iran