Sublethal effects of cadmium on some selected haematological parameters of Heteroclarias (a hybrid of Heterobranchus bidorsalis and Clarias gariepinus)

Abstract

Experiments were conducted to ascertain the sublethal effects of waterborne cadmium at 0.5 and 1.0 mg L-1 on a freshwater fish Heteroclarias (a hybrid of Heterobranchus bidorsalis and Clarias gariepinus) following a 15 days exposure in a renewal static bioassay system. The effects were assessed by examining the haematological profile. Exposure to cadmium caused a dose-dependent decrease in haemoglobin, haematocrit and erythrocyte counts. These changes are obvious indication of anaemia of the normochromic type. The erythrocytic indices of MCHC, MCH and MCV were similarly decreased apart from one case. Differential leucocyte count and erythrocyte sedimentation rate were also affected. Plasma levels of protein were lowered and glucose levels were elevated in the exposed fish when compared to the control. The results of this study highlight the stress to which freshwater fish are exposed through the uncontrolled discharge of heavy metals in the aquatic environment. © 2006 Academic Journals Inc.