In the line of duty

Cleaner wrasses perform an important function on reefs by removing parasites from larger fishes. Many types of fish seek out the services of cleaner wrasses and in some instances may lead to the establishment of "cleaning stations" where larger fish will queue up to be cleaned by several cleaner wrasses. Many of these cleaning stations are permanent and most fish will return to the same place to be cleaned. Cleaner wrasses advertise their availability by swimming in a quick jerking motion which is recognized by potential clients. In this symbiotic relationship of trust and mutual benefit the small wrasses will even enter the mouth and gill cavities of predatory fishes, just as this wrasse has done with a large honeycomb moray eel.