Considering the effects of dietary nucleotides on growth and metabolism, this study was conducted to determine the effect of different levels of this nutrient on the sources of the body needed energy, and growth performance of common carp. Fish with average (±SD) weight of 7.5±0.2g were fed to five levels of dietary nucleotides containing 0, 0.1, 0.2, 0.3 and 0.4 percent for 8 weeks. Fish were fed 5 times daily according the satiation. After 56 days, the results showed that the level 0.2% nucleotide had the highest growth rate in terms of weight and length, but other parameters such as body weight, specific growth rate and feed conversion ratio, differences were not significantly changed. Biochemical analysis of serum parameters and proximate analysis showed that the physiological function of fish affected by different levels of nucleotides whereas in the energy supply sources, including glucose, triacyleglycerol, total protein and albumin there were no significant difference in cholesterol and lipid content of carcass. This study conveys a positive effect on the biosynthesis of dietary nucleotides on energy sources and growth functions, while the common carp has ability to synthesize this substance into the body, the level of 0.2% in the diet can affection *Corresponding author sufficient effect on growth and some biochemical indices
