A cleaner butterflyfish that works the Cocos hammerhead stations.
A butterflyfish that works as a cleaner, and the reason the Cocos hammerhead dives are possible in the form they take.
Hammerheads come to fixed points on the seamounts to be cleaned, and barberfish are the species doing most of that work, along with king angelfish. The sharks slow, open their mouths and flare their gills; the barberfish move over the head and gills removing parasites. Without the stations the sharks would have less reason to come within diving depth at all.
Yellow-bodied with a dark snout and a dark bar through the eye. Common on the rocky reef at both destinations, but it is the behaviour at the stations rather than the fish itself that most divers remember.
Stations are used repeatedly and are usually at a specific rock or ridge on the seamount. Divers who settle below and downcurrent of a station, and stay still, see the cleaning continue; movement toward it ends the interaction.
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.