Haematological responses in a fresh water fish to experimental manganese poisoning

Blood dyscrasia in a fish exposed to experimental manganese poisoning is described. Colisa fasciatus, a fresh water teleost, showed significant decreases in the total erythrocyte count, number of erythrocytes/1000 blood cells of all types, and in the hepatosomatic index (relative liver wt) after exposure for 90 h to 2500 mg/l manganese sulphate; the 96 h LC50 value was 2850 mg/l. The exposure also evoked leucocytosis due to an increase in the number of small lymphocytes. Other haematological characteristics, viz., total count of thrombocytes, distribution of immature red blood cells, thrombocytes and large lymphocytes/1000 blood cells, haematocrit, erythrocyte sedimentation rate, haemoglobin, and clotting time, did not differ significantly from the controls.