Acanthurus coeruleus also known as the Atlantic blue tang surgeonfish (or the blue tang for short) is a surgeonfish found commonly in the atlantic ocean
Although the body of the fish can vary in shaded from light to dark blue, both the dorsal fin and the anal fin are covered in bright blue on their edges. Their colors change during growth from a yellow juvenile and the blue adult phase.
Acanthurus coeruleus is common off of Florida, the Bahamas, and other places in the Caribbean sea. It is also common in the Gulf of Mexico. they are found south to Brazil and north to New York and eat krill. (text source: wikipedia)