Why Do Cleaner Fish Cheat?

Our next project will aim to investigate if there is a relationship between time of day and occurrence of cheating behaviour in the common cleaner wrasse, Labroides dimidiatus. Cleaner wrasse have a mutualistic relationship with their client reef fish where the feed off parasites on the client’s skin. Clients known to use the services of cleaner fish diets often consist of fish but due to the long-term benefit of not consuming these fish they do not prey on the cleaner wrasse. Male cleaner wrasses are harem holders and normally live in static ‘cleaning stations’, cleaning in pairs.

Cleaner wrasse have been found to prefer client mucous, obtained from biting clients, over the ectoparasites they feed on. This biting behaviour is known as cheating in response to cheating behaviour, clients have been found to jolt and terminate the interaction or chase the cleaner wrasse in response.

What is not fully understood is the reason why cleaners cheat. Time of day may affect cleaner wrasses likelihood of cheating as parasite load decreases throughout the day when the cleaner fish is still active therefore the cleaner wrasse’s energy requirements may not be met as the day progresses.