COmmon carp (Cyprinus carpio) were subjected to sublethal doses (1/4 and 1/2 LC50) of copper (0.239 & 0.478 ppm); cadmium (1.278 & 2.556 ppm); and zinc (2.444 & 4.889 ppm) separately or in mixtures of them for 7, 15, 30 and 90 days. Copper, cadmium and zinc caused significant decrease in the erythrocytic (RBCs) count of fish subjected to 1/4 LC50 of each of them on the 15th and 30th days. The decrease was also recorded after 15 days in fish exposed to 1/4 LC50 of Cu + Cd and Cu+Zn. Also RBCs in fish exposed to the high dose (1/2 LC50) of Cu, Cd, Zn and mixture of them was decreased significantly on the 30th day. The RBCs count was more affected by the higher concentrations of heavy metals studied and the longer time of exposure. Heamoglobin (Hb) content showed significant decrease on the 30th day of exposure to low dose of Cu, Zn, Cu + Zn and Cd + Zn. The decrease was also recorded on the 90th day in
fish exposed to Cu+ Cd + Zn. In the same manner, Hb in fish exposed to higher concentration of Cu, Cd, Zn and Cu + Zn was significantly decreased on the 90th day and the decrease was recorded on the 30th day in fish subjected to 1/2 LC50 of Cu and Cd + Zn. Packed cell volume (PCV) in fish exposed to 1/4 LC50 decreased significantly on the 15th and 30th days of exposure to Cu, on the 30th day of exposure to Zn and on the 7th and 90th ays of exposure to Cd + Zn. The decrease was also recorded on the 30th day in fish subjected to high dose of Cu, Cd + Zn and Cu + Cd + Zn. While fish exposed to high concentration of Cu and Cd recorded significant increase in PCV values. The corpuscular indices, mean corpuscular volume (MCV); mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) changed to compensate the changes in the RBCs Hb and PCV values. These resulted in macrocytic
hyperchromic or macrocytic hypochromic anaemia.