Cleaner fish are fish that provide a service to other fish species by removing dead skin and ectoparasites. This is an example of mutualism, an ecological interaction that benefits both parties.
The cleaner wrasse Labroides dimidiatus
removing dead skin and external parasites from the grouper Epinephelus tukula
A wide variety of fishes show cleaning behaviors. They include wrasse, cichlids, catfish, and gobies, as well as by a number of different species of cleaner shrimp.
There is also at least one predatory mimic, the sabre-toothed blenny. It mimics cleaner fish but in fact bites off pieces of fin.