Cleaner fish

Cleaner fish are fish that provide a service to other fish species by removing dead skin and ectoparasites.Curry O. 2005. Morality as natural history. University of London Ph.D. dissertation. Accessed 2009-06-08. This is an example of mutualism, an ecological interaction that benefits both parties. 

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.

 References 

Category:Ray-finned fish