THE EFFECT OF COMBINED TREATMENT OF COPPER AND CADMIUM ON THE HEAVY METAL CONCENTRATION AND HISTOPATHOLOGY OF CARASSIUS AURATUS

Heavy metal copper (Cu) and cadmium (Cd) are common contaminants in water environment and dangerous to the existence and edible safety of fish. In this study, laboratory simulated semi-static method was used to feed Carassius auratus by simultaneously adding Cu and Cd to the water. The concentrations of Cu and Cd were detected in different places of Carassius auratus. Moreover, the effect of Cu and Cd on different tissues of Carassius auratus was evaluated by histopathology. The results showed that liver, gill, gut and muscle of Carassius auratus had enrichment of Cu and Cd. The Cu concentration was significantly higher than Cd in Carassius auratus. With increasing Cd concentration in water, Cd concentration in the tissues of Carassius auratus gradually increased. However, Cu concentration in Carassius auratus showed a declined trend. After fed 14 days with Cu and Cd concentrations of 0.15 and 0.20 mg/L, respectively, the muscle of Carassius auratus had a Cd concentration of 0.13 mg/kg, which exceeded the limit value of 0.10 mg/kg in Chinese industrial standard on " the limit of poisonous and harmful material in aquatic products”. After combined treatment of both Cu and Cd, the tissues of Carassius auratus showed various pathological changes. Moreover, the damage degree increased with increasing concentrations of Cu and Cd. Liver tissue showed hemagglutination, lipoidosis and cell vacuolation. Gill tissue manifested hyperplasia, edema and mucosal swollen. Gut tissue included goblet cell swollen, columnar cell hyperplasia, lamina propria vacuolation, mucosal erosion and villi exfoliation. Muscle tissue showed myofiber fracture, aggregation, collapse and dissolution, as well as broad gap of myofiber. Cu and Cd accumulated in Carassius auratus, and histopathological damage was present in the tissues. Moreover, the higher concentration, the more obvious damages, and these were mainly due to the accumulation of Cd in the body. This study can provide data support for the growth condition and edible safety of heavy metal pollution on Carassius auratus.