EFFECT OF COPPER ON THE DIFFERENTIAL WHITE BLOOD-CELL COUNTS OF THE MOZAMBIQUE TILAPIA (OREOCHROMIS-MOSSAMBICUS)

An increase in the number of leucocytes (leucocytosis) is a normal rea ction of the fish body, against attacks of foreign substances, such as copper, which can alter the normal physiological function in fish. Si gnificant increases in the number of lymphocytes (lymphocytosis) and e osinophils (eosinophilia) combined with significant decreases in monoc ytes (monocytopenia) and neutrophils (neutropenia), are indicative of changes (infections) that set in after short-term (96 hr) exposure to copper. This finding was confirmed by the number of leucocytes of Oreo chromis mossambicus that increased at both temperatures, to protect th e body against infections that may have been caused by copper.