This study has been carried in order to determine the effect of dietary combinatory probiotic and prebiotic on some hematological parameters, serum biochemical and resistance to environmental stresses of Benni (Mesopotamichthys sharpeyi) juveniles. 600 fish with initial average weight of 3.83±0.2 g were stocked in 15 tanks. Five dietary treatments included treatment 1 (control) which was fed with basal commercial diet only and the other treatments 2 to 5 containing 0.5, 1, 1.5 and 2 g Entrococcus faecium (5×1011 CFU/KG) and Inulin per kg of diets, respectively. The experimental trail was carried out in triplicate for a period of 60 days. Experimental fish were fed (3% body wet weight) daily at 08:00, 13:00 and 18:00. The results of the present study demonstrated that the significantly increased the hematological parameters among the treatments. The hematocrit and white blood cells were increased with increasing by combinatory dietary levels. However, the red blood cells and hemoglobin were decreased. In addition, total protein and globulin indices significantly increased with increasing dietary levels. However, cholesterol and triglyceride levels of experimental fish decreased among treatments. The results of environmental stresses (thermal, salinity and pH stress) showed that resistance and survival rate of fish were significantly higher in the treatments with higher dietary probiotic and prebiotic than the control treatment. The present study revealed that the best results for M. sharpeyi juveniles were achieved at 1.5 g to 2 per kg dietary Entrococcus faecium (5×1011 CFU/KG) and Inulin based on improved of hematological parameters, serum biochemical composition and resistance against the environmental stresses