It's all in the name; the cleaner wrasse has one job and one job only, to clean. All species of fish need to be cleaned, or, to be more precise, for someone to remove its dead skin cells and parasites that attach themselves to the fish as they sleep at night, hidden amongst the rocks and coral.
This is where the cleaner wrasse comes in. Its job is to remove all this grime by eating it off. Basically, it works for food and gains diplomatic immunity from all species, even the predators.
Fish of all sizes will arrive at a cleaning station which is actually advertied by the wrasse doing an inviting dance. Once the fish has chosen its station, the team of wrasse get to work. Usually led by a male with a team of female workers, he manages his employees, even admonishing them if they get a bit greedy and bite their customers followed by apologising to his client by giving them a fin massage. Fish can watch the cleaners in action and, if they don't like the look of it, they move on to another station just down the coral. However, if you are a diver they are very annoying if you have some open wounds or scabs as they will see that as something that need a good cleaning and, before you know it, MUNCH! They have gobbled up your scab.