Copper Compound Studied for Protecting Catfish Eggs

Farmers who raise channel catfish use a chemical called copper sulfate to cut excessive growth of oxygen-robbing algae in ponds. This helps keep the fish healthy and production costs down.

Now, Agricultural Research Service scientists and cooperators are beginning to explore additional uses of the copper compound that might make the fish less costly to raise. Researchers at the ARS Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, Ark., are working under a two-year cooperative research and development agreement with Phelps Dodge Refining Corp., El Paso, Texas.

The cost savings generated by the copper compound would begin with catfish eggs. Without some preventive medicine in U.S. fish hatcheries, less than half the estimated one billion catfish eggs produced each year would ever become small fry to stock ponds, much less become tasty entrees. The egg-destroying culprits in hatchery tanks are cottony water-borne fungi. These organisms cause much of the investment in four- to eight-year-old catfish broodstock to go down the drain.

Since the 1980s, fish farmers have had only one U.S. Food and Drug Administration (FDA)-approved therapeutic drug, formalin, available to save the eggs. Copper sulfate is a less expensive, less smelly substance that’s easier than formalin to apply safely. But does copper sulfate work without harming the young hatchlings? That’s a question the cooperative research will address.

Before entering the agreement, Phelps Dodge was seeking FDA approval for copper sulfate as a treatment for a parasitic disease of fish called ichthyopthiriasis. FDA restricts use of therapeutic agents to diseases defined in an approved label claim, and only commercial companies are allowed to formally apply for FDA approval of their products.

Research collaboration between ARS and Phelps Dodge may provide an avenue to place copper sulfate, as a therapeutic agent, into the hands of fish producers.

ARS is the U.S. Department of Agriculture’s chief scientific research agency.

Scientific contact: Billy R. Griffin, ARS Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, Ark., phone (870) 673-4483, fax (870) 673-7710, bgriffin@spa.ars.usda.gov.