The Yellowfin surgeonfish or Cuvier’s Surgeonfish is one of the species of saltwater sea fish that change color as they get older. This peculiarity often leads to confusion when determining the membership of a species of fish. Young individuals and adults of the species have been classified as belonging to a different species. With the arrival of aquariums and the development of coral reef fish farming systems, specialists noticed that some of these fish, known with two or more scientific names, were actually all members of the same species. Only recently have zoologists begun to reveal the secret of their metamorphosis.
The name Yellow-tailed Acanthurus, which is not an Acanthurus in the strict sense of the word since it has been classified in the Hepatus genus deserves its name since the color of its tail is a beautiful yellow. When still young their length is less than 3.54 in (9 cm). After metamorphosis the color changes and the fish becomes completely purple blue or violet. Only the pectoral fins keeping a yellow fringe. The length of the adult Yellowfin ranges from 9.84 to 11.81 in (25 to 30 cm).
The Yellow-tailed Acanthurus, a typical inhabitant of the coral reefs, spends all of its life within a rather small personal territory. It is sedentary and eats living coral which it does by breaking calcareous branches with its teeth.