Alterations in Some Haematological Parameters of The African Snakehead: Parachanna africans Exposed to Cadmium

The haematological alterations produced on exposure of the African snakehead, Parachanna africans to the sublethal concentration (0.0, 0.1, 1.0 and 10.0 mg/L) of cadmium (Cd2+) for 21 days have been studied. Red blood cell (RBC) count, haemoglobin (Hb) concentration, haematocrit (Hct), the mean corpuscular haemoglobin (MCH) and the mean corpuscular volume (MCV) levels were decreased with an increase in exposure concentration, but the level of the mean corpuscular haemoglobin concentration (MCHC) was increased. These alterations could be attributed to haemolysis and impairment of haemoglobin synthesis, resulting in a hypochromic microcytic anaemia, induced by exposure to cadmium. Cadmium exposure also caused significant decreases in white blood cell (WBC) count. The primary consequence of the observed changes in total and differential leucocyte counts in stressed fish was attributed to suppression of the immune system and increased susceptibility to disease. Plasma glucose and total plasma protein concentrations were significantly decreased; showing that cadmium affects the fish energy metabolism. The present study thus confirmed that haematological parameters are very sensitive indicators of fish organism response to chemicals in this case cadmium.