Members of the genus Streptococcus are found quite often in the respiratory, genital and intestinal tracts of man and warmblooded animals, but rarely found in snails or fish. Investigation of fish kill in January 1992, on the Kissimmee River in Florida showed several hundred moribund and dead apple snails (Pomacea sp.), as well as a few dead largemouth bass (Micropterus salmoides), black crappie (Pamoxis negromaculatus) and chub suckers (Erimyson sucetta). Moribund snails were euthanized by submersion in a solution of Tricaine/methanesulfonate (MS-222), disinfected with povidine iodine and asceptically necropsied. Cultures were taken from the posterior kidneys, reproductive organs and the stomachs of the snails, as well as from the livers and kidneys of the moribund fish. A pure culture of a gram positive, catalase negative, non-motile viridans Streptococcus was isolated, on 5% ovine blood agar. Immersion of healthy snails of the isolated strain of viridans Streptococcus resulted in 87% mortality, demonstrating that this strain of Streptococcus is pathogenic to snails. Inoculation of the same Streptococcus into healthy bluegills (Lepomis macrochirus) resulted in 100% mortality. This Streptococcus grew at 25, 37, and 45°C, suggesting that the organism may have originated from warm-blooded animals.