Evaluation of Certain Blood and Biochemical Changes of Nile Catfish (Clarias gariepinus) Exposed to Mercuric Chloride with Particular Reference to Erythrocyte Morphological Anomalies

Sub-lethal toxicity of mercuric chloride (0.0002, 0.002, 0.02mg/L) in Nile catfish (Clarias gariepinus) after long-term (14 days) of exposure in the present study was investigated by measurement of some selective hematological and biochemical parameters with respect to erythrocyte morphological alterations. Experimental fish were set up with three groups for each concentration, plus the control group. Blood samples were collected from five individuals for each concentration after 14 days of exposure. The hematological parameters analyzed were: total red blood cell count (RBC), hemoglobin concentration (Hb), packed cell volume (PCV), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin Concentration (MCHC), total platelets count, total white blood cell count (WBC) and differential leukocyte counts (neutrophil, eosinophil, lymphocyte, monocyte and basophils). Fish exposed to 0.02mg/L Hg showed a significant decrease in RBC count, Hb, MCHC and platelets number than control groups (P<0.05) with moderate elevation in PCV, MCV, WBC, neutrophil, eosinophil, lymphocyte, glucose and cortisol levels compared with the control groups (P<0.05). However, fish exposed to the other two low concentrations showed no toxic effects. Hg at the concentrations studied was toxic to Nile catfish (Clarias gariepinus) at the higher dose only (0.02mg/L) after long term exposure.