Fourty fresh water grass carp fish weighing about (35.75 ± 0.60) g were obtained from fish aquaria by, Marine Science Center, University of Basrah, Iraq. First the. Fish were individually examined for external necrosis and infections. Healthy and see it very active in the study. The physiochemical characteristics of water used for acclimation in control and polluted water that were used for the fish of experiment were daily recorded. The results of the present study show that the blood parameters ( RBC and WBC counts and Hb content) for fresh water grass carp fish were greater than those values of polluted water grass carp fish and also show increased number of dead fish among polluted grass carp, in reverse of fresh water ones. Physicochemical characteristics of water did not affect the result