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the number of new water acres used for catfish production in the delta region of west-central Mississippi.2 This increase in production was reflected by the establishment of the fish health diagnostic laboratory at Belzoni in June 1986 and the subsequent increase in the aquatic diagnostic case load of the Mississippi Cooperative Extension Service. The fish health diagnostic laboratory case load has remained relatively con-stant since 1986, which may reflect a decreasing growth rate of this industry in Mississippi or failure of producers to seek diagnostic laboratory support. However, the industry con-tinues to expand within Mississippi and in adjoining states and other areas of the country. Bacterial diseases continue to be a major economic factor for commercial catfish farmers. Motile Aeromonas septice-mia, columnar-is disease (Cytophaga spp.), and enteric sep