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Upper Midwest Environmental Sciences Center

Fisheries Restoration

Field Effectiveness of Terramycin 343® (Oxytetracycline HCL) to Control Mortality in Coolwater and Warmwater Finfish due to Flavobacterium Columnare

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Impact of UMESC Science

The results from this study may lead to an expansion of the Terramycin 343® label allowing for the use of the drug to control mortality in coolwater and warmwater finfish due to Flavobacterium columnare. Label expansion would enhance coolwater and warmwater finfish production on all hatcheries throughout the United Sates.


Columnaris disease caused by the Gram negative bacterium Flavobacterium columnare (Fc) results in severe mortalities in cultured salmonids, ictalurids, cyprinids, and centrarchids (Holt et al. 1975; Bader and Starliper 2002). Flavobacteriaceae species are ubiquitous, opportunistic pathogens in the aquatic environment. The genus Flavobacterium contains organisms which have been assigned to the various genera of Chondrococcus, Cytophaga, and Flexibacter (Bernardet et al. 1996). 

Presently, hydrogen peroxide (35% Perox-Aid® For Fish) is a therapy approved by the Food and Drug Administration’s Center for Veterinary Medicine (CVM) to control mortality associated with external Fc outbreaks in freshwater-reared coolwater finfish, channel catfish Ictalurus punctatus and rainbow troutOncorhynchus mykiss. Florfenicol (Aquaflor® CA1, Type A medicated article, 50% w/w) is approved for use as medicated feed for channel catfish to control mortality associated with columnaris disease ( Other treatments that have been reported but are not approved by CVM include sodium chloride, quaternary ammonium compounds, potassium permanganate, oxalinic acid, chloramine-T and oxytetracyline hydrochloride (Bader and Starliper 2002;


Determine the effectiveness of Terramycin 343® (oxytetracycline HCL; OTC-HCL) administered as a static immersion bath to control mortality in coolwater and warmwater finfish due to Flavobacterium columnare.


Bader, J.A., and C.E. Starliper.  2002.  The genera Flavobacterium and Flexibacter. Pages 99-139 in J. L. Nielsen, editor.  Molecular diagnosis of salmonid diseases. Kluwer Academic Publishers, Netherlands.

Bernardet, J.F., P. Segers, M. Bancanneyt, F. Berthe, K. Kersters, and P. Vandamme. 1996.  Cutting a gordian knot: emended classification and description of the genus Flavobacterium, emended description of the family Flavobacteraceae, and proposal of Flavobacterium hydatis nom. nov. (Basonym, Cytophaga aquatilis Strohl and Tait 1978).  International Journal of Systematic Bacteriology 46:128-148.

Holt, R.A., J.E. Sanders, J.L. Zinn, J.L. Fryer, and K.S. Pilcher.  1975.  Relation of water temperature to Flexibacter columnaris infection in steelhead trout (Salmo gairdneri), coho (Oncorhynchus kisutch) and chinook (O. tshawytscha) salmon. Journal of Fisheries Research Board of Canada 32:1553-1559.

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