AN EPIZOOTIC OF EDWARDSIELLA-TARDA IN LARGEMOUTH BASS (MICROPTERUS, SALMOIDES)

Edwardsiella tarda, an opportunistic bacterial pathogen, was isolated from dying largemouth bass (Micropterus salmoides) during an epizootic in a eutrophic lake system, Lochloosa Lake, Florida, USA. Approximate ly 1,500 adult fish died over a 6-wk period during the late summer and early fall of 1991. A mixed population of aerobic bacteria (E. tarda, Aeromonas hydrophila, and Pseudomonas sp.) was isolated from deep cut aneous ulcers and intestines of moribund bass. However, E. tarda in pu re culture was the only bacterium isolated f rom several viscera of se veral fish; E. tarda may be the etiologic agent responsible for some e pisodes of seasonal mortality in largemouth bass.