Toxicity of cadmium to Parachanna obscura : As evidenced by alterations in hematology, histology, and behavior

Abstract

Fish of species Parachanna obscura are exposed to four concentrations of cadmium (Cd) (0.02, 0.06, 0.18, or 0.54 mg L−1). Acute toxicity test results after 96 h showed marked hematological, histological, and behavioral changes. Quantitative blood analysis revealed that white blood cell (WBC), packed cell volume (PCV), and platelets counts were linearly correlated with increasing Cd concentrations; however, blood haemoglobin (Hb) showed an inverse relationship, with higher Hb levels at lower Cd concentrations. Histological changes of the liver showed hepatic separation, bloody appearance, and deposition of a brownish-yellow substance, which increased with rising concentrations of metal. Behavioral changes observed included reduced activity, avoidance response, and deposition of a slimy-whitish film on the body of the fish, which increased with concentration and exposure time.