Submitted to: Aquaculture Magazine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1998
Publication Date: N/A
Citation: Interpretive Summary: Copper sulfate is used as a disease treatment in fish culture. Little attention has been given to the effect the treatment has on treated fish. Channel catfish were exposed to waterborne copper sulfate for 24 hours in a treatment simulation. Changes in plasma carried stress indicators, the uptake of copper by the liver, and the response of liver tissue to the exposure were measured. There was an increase in plasma cortisol, which suggests the treatment represents a physiological stress for the fish; increassed plasma cortisol is a hallmark indicator of stress in most animals. Copper binding protein production was stimulated, but enzyme testing didnot reveal any cellular damage to the liver as a result of the treatment.
Technical Abstract: Copper sulfate is frequently used as a general biocide in the aquaculture industry. The acute effects of copper sulfate on sublethal endpoints of stress and tissue damage in channel catfish have not been explored previously. Consequently, the purpose of this study was to examine the effects of a therapeutically relevant dose of copper sulfate on plasma cortisol, hepatic metallothionein expression, hepatic copper content and plasma concentrations of aspartate aminotransferase (AST). Exposure of prespawn juvenile catfish to 1.7 mg/L as copper sulfate (326+9.4 ug/L copper; 175-180 mg/L CaCo3; pH 7.45) led to time-dependent increases in hepatic MT expression, hepatic copper content as well as plasma cortisol concentrations. Exposure to a one hour confinement stress led to a redistribution of copper to the liver but no significant increases in hepatic MT or plasma cortisol after 23 hours. Neither stress nor copper exposure caulsed liver damage as measured by AST. The parallel expression of hjepatic ME with plasma cortisol and hepatic copper residues suggests that MT may serve aas a useful indicator of acute stress and acute exposure to copper sulfate in channel catfish.