A large grey surgeonfish with yellow pectoral fins and a yellow band through the eye, grazing sand and rubble.
To 70 cm, commonly 50, which makes it the largest true surgeonfish in the world. Purplish-grey to purplish-brown in life, though it looks greyish-brown once dead, which is why descriptions conflict. Two marks: a broad dull yellow band running from the snout through the eye, and a yellow outer third to the pectoral fin, which is very visible as the fish swims. There is a white bar across the base of the tail, and the tail is strongly concave. Old fish can look almost uniformly dark purple with the yellow marks muted.
The elongate surgeonfish has recently turned up in the eastern Pacific and is the live confusion. It is more slender and has no yellow on the outer pectoral fin.
It is more tolerant of turbid, sandy and lagoon habitat than most surgeonfish, and takes detritus and diatoms off sand as well as grazing algae. It lives between 1 and 100 m and is usually between 5 and 90. It is a big fish with a correspondingly big tail blade; the risk is from handling.
The Smithsonian calls it the purple surgeonfish, and it is also called the ringtail surgeonfish.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.