Like any animal, a fish can develop skin problems, become afflicted with parasites and get generally dirty. Without the ability to take care of any of these problems themselves, some fish have developed a mutually beneficial relationship with one another.
Certain species of fish are known as cleaner fish. They provide a service to other fish (even sharks) by removing parasites and dead skin from their bodies and food particles from their mouths. It’s mutually beneficial because the cleaner fish feeds on what it removes while the client fish reaps the health benefits.
|A pair of cleaner wrasses go to work on a client|
Other marine animals that provide a similar service are several types of gobies and cleaner shrimp.