Chromium (III) induced haematological alterations in Indian common carp, Labeo rohita (Ham.)

The principle source of chromium in water bodies is discharged from industries which use large amount of chromates or dichromates. The freshwater fish, Labeo rohita was used as a model in the present studies to investigate the responses to chromium metal salt contamination in water bodies as it is the most common fish consumed widely in India. Haematological tests were carried out as these are the important diagnostic tools and are equally valuable as indicators of disease or stress due to pollutants and environmental fluctuations. The fishLabeo rohita were exposed to sublethal concentration of chromium chloride for 10, 20 and 30 days to study alterations in certain haematological parameters. The parameters under study were total erythrocyte count (TEC), haemoglobin (Hb gm%), total leucocyte count (TLC), differential leucocyte count (DLC) and pack cell volume (PCV). The studies revealed that chromium chloride-treated Labeo rohita exhibited decreased levels of total erythrocyte count (TEC), haemoglobinn (Hb gm%) and PCV whereas, total leucocyte count (TLC) was increased under thestress of chromium metal The decreased WBC count found after 30 days along with depleted Hb content and RBC count indicate dysfunctioning of haemopoietic systems along with dysleucopoiesis. Leucocytosis observed after 10 and 20 days exposure has been considered to be an adaptation to meet stressful conditions by animals. Increase in macrophages and basophils appears to be protective response during chromium exposure. An increasing trend in the mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were evident in fish exposed to sublethal doses of chromium chloride when compared with the control.