Submitted to: Annual Eastern Fish Health Workshop
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2004
Publication Date: March 22, 2004
Citation: Darwish, A.M., Straus, D.L., Griffin, B.R. 2004. Copper sulfate target animal safety in channel catfish [abstract]. Annual Eastern Fish Health Workshop. p. 71. Technical Abstract: A histological study was performed to evaluate the effect of waterborne exposures of channel catfish (Ictalurus punctatus) to copper sulfate (CuSO4) as a therapeutant. Channel catfish were exposed daily for 11 consecutive days to three concentrations of CuSO4 representing one, three and five times the recommended therapeutic level (2.91, 8.71 and 14.55 mg CuSO4/L) based on the total alkalinity of 291 mg/L (CaCO3). Copper sulfate was applied in flow through tanks and more than half the copper was reduced in 1 h similar to the elimination rates in ponds (this is due to the rapid uptake of copper by aquatic plants or algae and the binding to organic and inorganic material). The exposed fish did not exhibit any mortality, clinical signs or gross or histological lesions in the following tissues: gill, liver, anterior and posterior kidney, spleen, axial muscle with attached skin, pyloric intestine, heart, swim bladder and cornea. The absence of histological lesions was attributed in part to the brief daily exposure to Cu++ (the toxic form of copper), the use of alkalinity (> 50 mg/L) to calculate of the therapeutic dose, and the moderate hardness of the well water used which is essential to maintain a normal gill function. The results of this study suggest that the use of CuSO4 as a therapeutant is safe provided that the dose of copper applied is considered in relation to the total alkalinity of the water. The presented target animal safety study followed an approved protocol by the Food and Drug Administration (FDA) to support the data package required for the future FDA-approval of copper sulfate as an aquaculture therapeutant in the United States.