What is the term for the relationship where a cleaner fish removes parasites from a larger fish?

The relationship in which a cleaner fish removes parasites from a larger fish is called cleaning symbiosis. In the classic arrangement, the small cleaner gains food while the larger client has parasites and unwanted tissue removed.

Many cleaner fish operate at specific locations called cleaning stations. A client fish may adopt a stationary posture while the cleaner examines its skin, fins, or gill chambers. Cleaner wrasses and cleaning gobies are among the best-known examples, although similar services are provided by other fish and cleaner shrimps.

The interaction is often described as mutualism because both animals can benefit. However, biologists have debated whether every cleaning interaction is genuinely mutualistic. Some cleaners occasionally eat mucus, scales, or healthy tissue, and predatory fish such as the sabre-toothed blenny can mimic cleaners in order to approach and bite their clients.

“Mutualism” is therefore a related ecological description, but it is broader: it refers to any interaction benefiting both species. “Cleaning symbiosis” is the more precise name for the parasite-removal relationship described here.