Toxic effects of copper sulfate and copper nanoparticles on minerals, enzymes, thyroid hormones and protein fractions of plasma and histopathology in common carp Cyprinus carpio

Differences in toxicological effects of dissolved copper and copper nanoparticles were studied in common carp, Cyprinus carpio. The fish were exposed to 0.25 mg L−1 copper as copper sulfate (0.25Cu), 0.25 mg L−1 copper as copper oxide nanoparticles (0.25NCu) and 25 mg L−1 copper as copper oxide nanoparticles (25NCu) over 14 days. Plasma biochemical, enzymatic and hormonal characteristics, and liver and kidney histopathology were examined at the end of the experiment. The results showed that both forms of copper had no significant effects on plasma calcium levels, however, significantly increased plasma phosphorous levels, compared to control group (no added copper). Plasma alanine transaminase (ALT) activity increased in 0.25Cu and 25NCu treatments compared to the control and 0.25NCu treatments. Nanoparticle copper exposure significantly decreased plasma alkaline phosphatase (ALP) activity compared to the control and 0.25Cu treatments. Only copper sulfate exposure caused plasma aspartate transaminase (AST) elevation. Both copper forms increased plasma T4 and free T4 (FT4); however, copper sulfate effect was higher than nanoparticle copper. Copper sulfate exposure increased plasma albumin fraction, whereas, 25 mg L−1 copper nanoparticle exposure increased plasma α2-globulin fraction compared to the control. Both copper forms damaged the fish liver and kidney, however, copper sulfate caused more severe damages compared to nanoparticle copper. Overall, except for plasma ALP and α2-globulin fraction, dissolved copper seems to be more toxic than nanoparticle copper in common carp.