The haematological (Hb, RBC, WBC) and biochemical (protein and glucose) profiles of a freshwater fish Catla catla were studied under sub-lethal toxicity of cadmium chloride for 25 days (Treatment I). In addition, the influence of zinc on cadmium toxicity was investigated for haematological and biochemical parameters (Treatment II). In both the experiments, blood haemoglobin and plasma protein level decreased in the treated fish. However, WBC, RBC and plasma glucose levels were increased in Treatment I, while Treatment II showed mixed results. In Treatment II the alterations of both haematological and biological parameters were minimal compared with Treatment I. The alterations of these parameters are discussed as non-specific biomarkers against metal toxicity in aquatic organisms.