Manny Puig, occasional cast member of MTV's Jackass and Wildboyz show was attacked by a Goliath grouper on one of the episodes. It was a pretty big fish, sucked in his arm all the way to the shoulder. Its in one of the episodes although i couldn't find the clip i found a link to another story that cost a man his life:
http://www.cdnn.info/news/eco/e060915.html