In this experiment, the effect of different levels of malic acid (0.0, 2.5, 5, 7.5 and 10 g/kg diet) was evaluated on hematological, biochemical and immunological indices of juvenile Siberian sturgeon (Acipenser baerii). For this purpose, a total number of 375 fish (33.72 ± 0.60 g initial weight; mean ± S.E.) were randomly assigned to 15 circular concrete tanks (1.85 m diameter and 0.25 m depth). The fish were distributed in 5 treatments with 3 replicates and were fed during 8 weeks. The results of hematological showed that there was no significant difference among treatments in the number of red blood cells, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration(P>0.05). There was a significant difference in glucose, total protein and globulin levels among treatments (P<0.05). The lowest level of glucose, total protein and globulin were observed in treatment of 7.5 g/kg. There was no significant difference among treatments in other parameters including albumin, cholesterol, triglyceride, aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase (P>0.05). The results of immune indices showed that there was no significant difference in white blood cell count and IgM (P>0.05). The highest amount of total immunoglobulin and lysozyme activity was observed in treatment of 2.5 g/kg which had a significant difference with control treatment (P<0.05). Based on the results obtained, it can concluded that the malic acid used in this study had a minor effect on improving some blood and immune indices of juvenile Siberian sturgeon.