This study was conducted to determine the effects of using Spirulina and Chlorella instead of fish meal on the growth, feed utilization, digestibility and digestive enzyme activity of common carp (Cyprinus carpio). For this purpose, 25% fish meal was added to the control diet, 25% Spirulina to the SP diet and 25% Chlorella to the CL diet as the main protein source. In the 3×3 planned experiment, fish with an average weight of 1.98±0.10 g were fed with isonitrogenous and isolipidic formulated diets until satiation for 60 days. At the end of the experiment, higher final body weight and specific growth rate were obtained in the groups fed with diets containing Spirulina and Chlorella (p<0.05) and feed conversion was not affected by the main protein source in the diet. Lipid content in muscle tissue of fish fed with control diet was lower than that of the group fed with Chlorella containing diet (p<0.05). Microalgae addition to the diets significantly (p<0.05) increased dry matter, protein and lipid digestibility, as well as protease and lipase activity. The results obtained showed that Spirulina or Chlorella in Cyprinus carpio diets increased growth, nutrient digestibility and activity of digestive enzymes, and therefore, based on these parameters examined, Spirulina and Chlorella could be used instead of the entire 25% fish meal in the diet.