Cleaner fish coloration decreases predation risk in aggressive fangblenny mimics

Mimicry systems can be classified by the nature of fitness benefits obtained by the mimic, namely increased mating opportunities (reproductive), increased foraging potential (aggressive), or reduced predation risk (protective). However, there is increasing evidence that mimicry categories are not mutually exclusive and mimics can obtain benefits from more than 1 category. Here, I provide evidence that an aggressive mimic, the bluestriped fangblenny Plagiotremus rhinorhynchos, also benefits from reduced predation risk by resembling the juvenile cleaner wrasse Labroides dimidiatus, which are thought to be relatively immune from predation due to the mutualistic nature of cleaner–client interactions. Instead of removing ectoparasites from larger reef fish, bluestriped fangblennies approach and attack reef fish removing scales and dermal tissue. Fangblennies can switch between their mimic and nonmimic coloration within 5–10min, depending on whether their model (the cleaner wrasse) is present or absent. I found that mimic fangblennies increased their risk-taking behavior toward potential predators compared with nonmimic fangblennies. Mimics were also more likely to attack other reef fish in the presence of predators compared with nonmimics. Animals should only increase risk-taking behavior when they perceive the threat of predation to be low. Therefore, this study provides important evidence that cleaner coloration provides protection from predation to both cleaner fish and their mimics, and the benefits of aggressive mimicry of cleaner wrasse have to be reevaluated in the light of these data.