Abstract: Efficiency has been investigated of the increase diets nutritional value by adding selenium as microelement into diets Common carp fingerlings were studied using aquarium and cement tanks systems, which allowed feeding and continues measurement of growth parameters. In experiment 150 fingerlings each weighing approximately 7.5�0.23 g was carried out in aquarium and fed either normal diet (A. group) or diets supplemented with 0.08, 0.16, 0.32 and 0.64 mg kg ¹ of sodium selenite. In experiment 360 juvenile common carp, average weight 26.9�1.38 g was carried out in cement tanks and fed as in experiment. When selenium added to the diets and fed to the fish caused a significant increase in weight gain and carp fingerlings growth rate was accelerated by 18-22% feed expenditure out by 17-18% as compared to the control diet. There are significant differences in survival rate were found between treatments, indicating that diets are likely to be responsible for increased survival rate, observed in fish fed diet supplemented with 0.24 and 0.32 mg kg ¹ Na₂SeO₃.5H₂O. The results of this study indicated that a diet supplemented, 0.16 and 0.32 mg kg ¹ of sodium selenite is important for growth and survival of common carp.