Picture is of a Pacific Sailfin Tang (Zebrasoma veliferum) caught off the coast of Florida. This is just one of the exotics that have been photographed while scuba diving over Florida Reefs. Some exotic hitch rides on boats and oil rigs, an issue that is just being addressed, but this one most probably was released from someones aquarium.
This fish was quite difficult to identify due to the fact that their coloration and color patterns can be so variable. Females grow larger than their male counterparts.
Sailfin Tang feed a variety of foods but mainly graze on algae.