EFFECTS OF COPPER AND LEAD ON SOME HEMATOLOGICAL PARAMETERS OF Oreochromis niloticus

Effects of sub-lethal concentrations of copper and lead on hematocrit and mean cell volume (MCV) levels and on erythrocyte numbers, erythrocyte and erythrocyte nucleus areas were determined after exposing Oreochromis niloticus to 4 ppm Cu and 0.2 ppm Pb over 7, 15 and 30 days. Micro-hematocrit methods were adopted in determining hematocrit levels and microscopic methods were used to determine MCV, erythrocyte numbers, erythrocyte and erythrocyte nucleus areas. Hematocrit and MCV levels and erythrocyte and nucleus areas increased significantly (P<0.05), whereas the erythrocyte numbers decreased under the effect of both metals at the exposure periods tested, except at 30 days of copper exposure. There was an increase in MCV levels under the effect of lead and an increase in erythrocyte and nucleus areas under the effect of both metals with increasing exposure periods. Prolonged exposure periods decreased other hematological parameters studied. Hematological parameters studied were higher in fish exposed to lead compared to copper during the experiments, except the erythrocyte area. It was concluded that both copper and lead caused significant changes in hematological parameters of O. niloticus which, in turn, affected the physiological conditions of fish.