Abstract

The effect of CaO in common carp Cyprinus carpio was studied. First group was exposured to cadmium chloride at concentration 1 mg/L for 7 day and then CaO at concentration 160mg/L was added to this environment, second group exposured to CaO 160mg/L and cadmium chloride 1 mg/Lat the same time ,the experiment is continue for (16) day, third group only exposured to cadmium chloride, fish on the fourth group was exposured to cadmium chloride, fifth group considered control group. Histopathological changes hyperplasia in the gills filaments which lead to adhesion between them at the 7 day, there was absence of any pathological changes induced by cadmium chloride in the gills of the fish at the second group at the 16day from the experiment, with significant decrease (P<0.05) in the stress index at the 7 day in compare with the other group.