The Yellowfin surgeonfish one of the species of salt water sea fish that change color as they get older. When still young it deserves its name since the color of its tail is a beautiful yellow. After metamorphosis the color changes and the fish becomes completely purple blue or violet, only the pecotral or side fins keeping a yellow fringe. They are the largest of their species, reaching up to over 27 inches and are found over the largest geographic area of the globe. They are also found at some of the greatest depths, having reportedly been observed by submarines at 295 feet deep. Their eating habits lean towards crushed living coral, however they love to snack on the algae on the sides of the boats giving us a chance to check them out up close!