Asymmetric cheating opportunities and partner control in a cleaner fish mutualism

Cleaning interactions on reefs were observed and scored for cheating — the cleaner taking client mucus, indicated by the client jolting — together with the client’s response: leaving, chasing the cleaner, or continuing. Responses were compared between clients with and without alternative cleaning stations available.

Studied in

Labroides dimidiatus

Sample size

observed cleaning interactions scored for cheating and client response

Clients responded to being bitten by leaving or by chasing the cleaner. Clients with access to alternative stations were more likely to leave; clients without were more likely to chase. Cleaners cheated less with clients that had leaving as an option.

• Observational: cheating is inferred from client jolts rather than directly observed at the mouth.
• Reef systems where alternative stations exist; the availability of options differs between sites.

• Cleaner fish

  Cleaners prefer client mucus to client parasites, so honesty needs enforcing. Clients that can go elsewhere leave; clients that cannot chase the cleaner instead — two mechanisms, chosen by what the client can do.