The combined effect of cadmium and copper induces bioaccumulation, and toxicity and disrupts the antioxidant enzymatic activities of goldfish (Carassius auratus)

An aquatic environment polluted with cadmium (Cd) and copper (Cu) has threatened fish health and adversely affected the aquaculture industry's sustainable development. The study revealed that exposure to Cd and Cu caused significant bioaccumulation in goldfish tissues, particularly in gills, intestine, and muscles. The bioaccumulation of these heavy metals increased with exposure time, with the highest levels recorded after 96 hours. This prolonged exposure led to a range of adverse effects on the fish's physiological functions. Hematological parameters, including white blood cells, red blood cells, and platelets, decreased significantly, indicating a compromised immune system. Conversely, some hematological parameters, such as hemoglobin and hematocrit, increased with exposure, suggesting a potential compensatory response. Biochemical parameters, including serum glutamic pyruvic transaminase, blood urea, and serum triglycerides, also increased with exposure, indicating liver damage and disrupted metabolic functions. Furthermore, the study found that antioxidant enzymes, including superoxide dismutase, catalase, and ascorbic acid, decreased significantly, while malondialdehyde concentration increased, indicating oxidative stress and lipid peroxidation. These findings collectively suggest that Cd and Cu exposure can cause significant toxicity in goldfish, affecting their hematological, biochemical, and enzymatic functions, and highlighting the need for further research into the effects of these heavy metals on aquatic organisms.