On tropical reefs, cleaning interactions, in which a fish or shrimp cleaner removes ectoparasites from a client fish, are common. Such cleaning interactions have been shown to reduce physiological stress in the clients. We asked whether the process of cleaning by a cleaner wrasse Thalassoma noronhanun modified a fish client’s risk assessment, hypothesizing that the benefits of being cleaned may modify the cost avoiding a potential disturbance or predator. We experimentally approached fish of two species (a parrotfish Sparisoma amplum and a squirrelfish Holocentrus adscensionis) when they were being cleaned and when they were not being cleaned, and measured the client’s flight initiation distance (FID) – a metric of risk assessment. Both client fish species tolerated ~30% closer approach when being cleaned. The body size of the client did not affect FID in either species, and the number of cleaners present did not influence FID of squirrelfish, but parrotfish who received cleaning from two cleaners had longer FID. These findings imply that fish being cleaned modify their risk assessment, and these results add to a list of potential costs fish clients face in this fascinating mutualism.

中文翻译：

---

客户礁鱼在被清洁时可以忍受更近的人类接近

在热带珊瑚礁上，鱼或虾清洁剂从客户鱼身上去除外寄生虫的清洁相互作用很常见。这种清洁互动已被证明可以减少客户的生理压力。我们询问清洁濑鱼 Thalassoma noronhanun 的清洁过程是否改变了鱼类客户的风险评估，假设清洁的好处可能会改变成本，避免潜在的干扰或捕食者。我们实验性地接近了两种鱼（鹦鹉鱼 Sparisoma amplum 和松鼠鱼 Holocentrus adscensionis）在它们被清洁和未被清洁时，并测量了客户的飞行起始距离 (FID)——一种风险评估指标。两种客户鱼类在清洁时都可以容忍约 30% 的近距离接近。客户的体型不会影响任何一个物种的 FID，在场清洁工的数量也不会影响松鼠鱼的 FID，但接受两个清洁工清洁的鹦嘴鱼的 FID 更长。这些发现意味着被清洗的鱼会修改他们的风险评估，这些结果增加了鱼客户在这种迷人的共生关系中面临的潜在成本清单。