I would guess it's a Sphaeroides species, but I'm not sure which one. It looks a little like S. annulatus, but that's an eastern Pacific species and I assume yours was caught in Florida. It's probably an easy enough task to put a name on it, but I'm afraid I'm not that much help at the moment. My library is packed away in boxes while I move house, and I was unable to find much of use on the internet. (I suspect yours is a juvenile, and the keys and photos I managed to dig up referred to adult coloration.) I'll let you know if I have any luck.
Tony