Title: Optimizing CuSO4 treatments for fungus control on channel catfish eggs Authors
|Steeby, James - MSU|
Submitted to: Journal of Aquatic Animal Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 31, 2009
Publication Date: July 16, 2009
Citation: Straus, D.L., Mitchell, A.J., Carter, R.R., Steeby, J.A. 2009. Optimizing CuSO4 treatments for fungus control on channel catfish eggs. Journal of Aquatic Animal Health. 21(2):91-97. Interpretive Summary: Copper sulfate is used in the catfish industry by hatchery managers to prevent fungus from growing on eggs while they are incubated in hatching troughs with flow-through well water. In this study, we found the optimum treatment rate for these managers to treat their eggs was 10 parts per million copper sulfate. 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. It is also needed by the FDA for data we are developing to get approval for legal use of copper sulfate in catfish farming.
Technical Abstract: This range-finding study determined the optimum concentration of copper sulfate (CuSO4) for fungus (Saprolegnia sp.) control on channel catfish Ictalurus punctatus eggs. The study consisted of five CuSO4 concentrations (2.5, 5, 10, 20 and 40 mg/L) and an untreated control. A single spawn was used for each replication (N=4). Eggs were treated daily until the embryos reached the eyed stage. The 23.5°C flow-through well water had total alkalinity of 219 mg/L, total hardness of 88 mg/L and the pH was 7.6. When hatching was complete for all viable eggs, fry were counted to determine the percent survival in each treatment. Fungus was severe in the untreated controls (2% survival). The optimum treatment of 10 mg/L CuSO4 daily was sufficient to control fungus (69% survival) and was significantly different from the controls. Very little fungus was present in treatments receiving 10 mg/L CuSO4 or higher except in one replication that had ~40% unfertilized eggs. The average survival in the 0, 2.5, 5, 10, 20 and 40 mg/L CuSO4 treatments were 2, 34, 50, 69, 59 and 51%, respectively.