|Steeby, James -|
Submitted to: Journal of Applied Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 2010
Publication Date: September 20, 2011
Citation: Straus, D.L., Mitchell, A.J., Carter, R.R., Steeby, J.A. 2011. Dose-confirmation of copper sulfate for treating fungus on channel catfish eggs at a commercial hatchery. Journal of Applied Aquaculture. 23(3):199-206. Interpretive Summary: This study is the third and final study to support a future FDA-approval of copper sulfate as a therapeutant to control fungus growing on catfish eggs. This compound is used in catfish hatcheries to treat eggs while they are incubated in hatching troughs. This study was a field confirmation of previous studies that showed treating eggs daily with 10 parts per million copper sulfate worked to keep fungus from growing uncontrolled and killing the eggs. This research is important for the catfish industry and will help the FDA in approving this low-cost, safe and effective compound for use in aquaculture.
Technical Abstract: This study at a commercial hatchery was required by the U.S. Food and Drug Administration to provide independent substantiation of the results of a previous laboratory dose confirmation study to control fungus (Saprolegnia spp.) on channel catfish Ictalurus punctatus eggs with copper sulfate (CuSO4). The study compared an untreated control group of eggs to eggs treated with 10 mg/L CuSO4 in a flow-through system; mean water temperature was 23.5 C. Eggs were treated once daily until the embryos reached the eyed stage (5 treatments). Hatching was complete by day 11 and fry were counted to determine the percent survival in each treatment. Fungus was identified by PCR as Saprolegnia spp. The mean survival in the control treatments was 4% and in the CuSO4 treatments was 40%; the latter survival was significantly higher, but not within the normal range of hatching survival expected due to a poorly performing spawn. This study confirms that 10 mg/L CuSO4 is an effective treatment to control fungus on catfish eggs when used daily until the eggs are eyed. However, continued treatment of eggs until hatching occurs may be warranted based on fungal growth rates observed after treatments were discontinued in this study.