Title: Laboratory dose confirmation of copper sulfate for treating fungus on channel catfish eggs Authors
|Steeby, James - MSU, THAD CHOCHRAN NWAC|
Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2008
Publication Date: August 3, 2009
Citation: Straus, D.L., Mitchell, A.J., Radomski, A.A., Carter, R.R., Steeby, J.A. 2009. Laboratory dose confirmation of copper sulfate for treating fungus on channel catfish eggs. North American Journal of Aquaculture. 71(4):333-338. Interpretive Summary: This study supports a future FDA-approval of copper sulfate as a therapeutant and is the second of three studies that are required. This compound is used in catfish hatcheries to prevent fungus from growing on eggs while they are incubated in hatching troughs. In a previous study, we determined the optimum treatment concentration needed. In this study, we confirmed that treating eggs daily with this optimum treatment (10 parts per million copper sulfate) was statistically different from not treating them. This rate is very low and copper is flushed out of the troughs within a few hours. Research like this is important information that is needed by the catfish industry to fight fungus problems on eggs.
Technical Abstract: Two dose confirmation studies are required by the U.S. Food and Drug Administration to verify the effectiveness of a potential candidate to gain approval as a new animal drug; the studies provide independent substantiation of the results. This laboratory study was designed to compare an untreated control and 10 mg/L copper sulfate (CuSO4) to control fungus (Saprolegnia spp.) on channel catfish Ictalurus punctatus eggs at 23.5 C in a flow-through system. Eggs were treated once daily until the embryos reached the eyed stage (5 treatments). When hatching was complete for all viable eggs (day 10), fry were counted to determine the percent survival in each treatment. Fungus identified morphologically and by PCR as Saprolegnia spp. was severe in the control treatments, resulting in 8% survival. The mean percent survival of hatched fry in the CuSO4-treated eggs was significantly higher (55%) and ranged from 27% to 71%.