A surgeonfish get its name due to two small spines located at either sides of the tail fin, used for defense against potential predators. When they feel threatened, they begin to shake the tail, at which point the two blades or spines will come out from the slot where they are located.
Blue Tang changes its color as he grows, from yellow to blue.
The Surgeon feature is that they show vertical lines on his body and fins, and Grey Surgeons can change color as the surgeons, but always keep the blue color around the eyes. may swim in loose aggregations that can include Blue Tang, Doctorfish and the Surgeonfish.