Abstract: For the study of the Effect of supplementing different dietary levels of antibiotic (Tylosin 20%) on the blood picture of common carp (Cyprinus carpio L.) an experiment was carried out. Fish were fed with a laboratorial manufactured diet with protein content of 31.04%, energy 1437 calories/kg, and an antibiotic Tylosin 20% added at different levels 0, 20, 60, 100 mg/kg B.W statistically red blood cells count (RBC) did not show great differences among treatments In spite of significant differences (p<0.05) between T2 and T4 treatment (3.03 x 106 mL, 3.17 x 106 mL), respectively white blood cells(WBC)did not record any significant differences among all treatments. While the count of differential white blood cells record significant differences(p<0.05) for the treatment T3 and T4 (68.67 and 0.69%) respectively in the lymphocytes, whereas there were not any significant differences among all experimental treatments in neutrophils, monocytes, eosinophils and basophils cells.