Vibro vulnificus is a common water-born bacteria in warmer climates. It is most commonly associated with food poisoning after eating raw clams/oysters. I think it also infects fish (talapia in particular?)

Just about any bacteria can cause life threatening septicemia (bacteria in the blood) given the right circumstances. I can say that here in the north, this was not even covered in textbooks so I don't think it is quite as common as the article lets on. Maybe I will do a little research. I just love reading bach issues of "Morbidity and Mmortality Weekly Review"