Haematological Anomalies in a Fresh Water Teleost, Colisafasciatus, on Acute Exposure to Cobalt

Abstract

In C. fasciatus, a freshwater teleost, exposure for 90 h to a sublethal concentration of 195 ppm (0.87 of the 96 h LC50 value) cobalt chloride elicited leukopenia due to reduction in the number of circulating small lymphocytes. The treatment also caused decline in blood clotting time with a concomitant increase in the abundance of circulating thrombocytes. No differences in total erythrocyte count, hematocrit, erythrocyte sedimentation rate and Hb values were found between the control and treated fish. The hepatosomatic index of fish increased significantly after exposure to Co. Results are discussed in terms of fish reaction to acute stress.