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ARS Home » Southeast Area » Stuttgart, Arkansas » Harry K. Dupree Stuttgart National Aquaculture Research Cntr » Research » Publications at this Location » Publication #200979
Title: Susceptibility of channel catfish, Ictalurus punctatus, to Edwardsiella ictaluri challange following copper sulfate exposure

Author
item Griffin, Billy
item Mitchell, Andrew

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2007
Publication Date: 9/12/2007
Citation: Griffin, B.R., Mitchell, A.J. 2007. Susceptibility of channel catfish, Ictalurus punctatus, to Edwardsiella ictaluri challange following copper sulfate exposure. Journal of Fish Diseases. 30:581-585.

Interpretive Summary: Edwardsiella ictaluri is a bacterial pathogen of channel catfish that causes serious economic losses for catfish producers. Copper sulfate is a chemical that is commonly used in fish production ponds as a means to control algae. This study has shown that channel catfish previously exposed to copper sulfate were significantly more resistant to a bacterial challenge with E. ictaluri than those not exposed to the chemical. These findings are promising but further studies will be required to show if a reduced number of disease outbreaks caused by the bacterium occur in experimental ponds where fish have been previously treated with copper sulfate.

Technical Abstract: Channel catfish, Ictalurus punctatus (Rafinesque) with or without a preliminary 24h exposure to 2 mg copper sulfate L-1, were challenged with 7.5 X 106 colony forming units L-1 of Edwardsiella ictaluri to determine the effect of copper sulfate on disease resistance. Catfish previously exposed to copper sulfate were significantly more resistant to the bacterial challenge than those not exposed. Catfish not exposed to copper sulfate suffered 35.5% mortality while catfish exposed to copper sulfate experienced 14.1% mortality. Copper concentrations were the same in tank waters of both exposed and control fish at the time of challenge eliminating the possibility that copper in the water may have been toxic to bacteria. Copper concentrations in freeze dried and ground tissues of unexposed, exposed, and purged channel catfish were highest in fish before copper sulfate exposures suggesting that elevated tissue levels of copper were not responsible for the increased resistance to bacterial challenge. Competition for sites of bacterial attachment to gill or epithelial cells may account for the reduction in mortality; although, this is not supported by the low copper content of fish tissue after copper exposure.