Britannica Sources used in this answer

How do cleaner fishes benefit from eating parasites on other fish?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Two wild horses graze on tall grass in the open prairie of Theodore Roosevelt National Park, with rolling badlands visible in the background. — Feeding behaviour Wild horses graze in the Badlands of North Dakota.

Cleaner fishes, such as those in the wrasse genus Labroides, benefit from their feeding behavior in two primary ways:

Nutritional Source: By removing and consuming parasites and dead tissue from the skin, gill chambers, and mouths of larger carnivorous fishes, cleaner fish secure a consistent food supply.12
Protection: This relationship is a form of mutualism. Because larger fishes recognize the cleaner fish as beneficial, they refrain from eating them. This allows the cleaner fish to operate safely within the territory of predators, often maintaining a designated "cleaning station" that larger fish visit regularly.12

In essence, the cleaner fish gains both sustenance and a level of safety from predators that it might otherwise lack, while the host fish benefits from improved health and hygiene.1