Predation risk is high for the many small coral reef fishes, requiring successful sheltering or other predator defence mechanisms. Coral-dwelling gobies of the genus Gobiodon live in close association with scleractinian corals of the genus Acropora. Earlier studies indicated that the low movement frequency of adult fishes and the development of skin toxins (crinotoxicity) are predation avoidance mechanisms. Although past experiments showed that predators refuse food prepared with goby skin mucus, direct predator–prey interactions have not been studied. The present study compares the toxicity levels of two crinotoxic coral gobies – Gobiodon histrio, representative of a conspicuously coloured species, and Gobiodon sp.3 with cryptic coloration – using a standard bioassay method. The results show that toxin levels of both species differ significantly shortly after mucus release but become similar over time. Predator preferences were tested experimentally in an aquarium in which the two gobies and a juvenile damselfish Chromis viridis were exposed to the small grouper Epinephelus fasciatus. Video-analysis revealed that although coral gobies are potential prey, E. fasciatus clearly preferred the non-toxic control fish (C. viridis) over Gobiodon. When targeting a goby, the predator did not prefer one species over the other. Contrary to our expectations that toxic gobies are generally avoided, gobies were often captured, but they were expelled quickly, repeatedly and alive. This unusual post-capture avoidance confirms that these gobies have a very good chance of surviving attacks in the field due to their skin toxins. Nonetheless, some gobies were consumed: the coral shelter may therefore also provide additional protection, with toxins protecting them mainly during movement between corals. In summary, chemical deterrence by crinotoxic fishes seems to be far more efficient in predation avoidance than in physical deterrence involving body squamation and/or strong fin spines.

中文翻译：

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与珊瑚相关的 Gobiodon 物种（Teleostei：Gobiidae）中的皮肤毒素影响捕食者的偏好和猎物的生存

许多小型珊瑚礁鱼类的捕食风险很高，需要成功的庇护所或其他捕食者防御机制。Gobiodon属的珊瑚虾虎鱼与Acropora属的scleractinian珊瑚密切相关。早期的研究表明，成鱼的低运动频率和皮肤毒素（crinotoxicity）的发展是避免捕食的机制。尽管过去的实验表明捕食者拒绝用虾虎鱼皮肤粘液制备的食物，但尚未研究过捕食者-猎物的直接相互作用。本研究使用标准生物测定方法比较了两种有毒珊瑚虾虎鱼的毒性水平 - Gobiodon histrio，代表显着颜色的物种，以及具有神秘颜色的 Gobiodon sp.3。结果表明，两种物种的毒素水平在粘液释放后不久就显着不同，但随着时间的推移变得相似。捕食者的偏好在一个水族馆中进行了实验测试，在这个水族馆中，两只虾虎鱼和一只幼年雀鲷与小石斑鱼 Epinephelus fasciatus 接触。视频分析显示，虽然珊瑚虾虎鱼是潜在的猎物，但与 Gobiodon 相比，E. fasciatus 显然更喜欢无毒对照鱼（C. viridis）。当瞄准虾虎鱼时，捕食者不喜欢一种物种而不是另一种。与我们通常避免有毒虾虎鱼的预期相反，虾虎鱼经常被捕获，但它们被迅速、反复且活着地驱逐。这种不寻常的捕获后回避证实了这些虾虎鱼由于它们的皮肤毒素而有很大的机会在野外幸存下来。尽管如此，还是消耗了一些虾虎鱼：因此，珊瑚庇护所也可以提供额外的保护，毒素主要在珊瑚之间移动期间保护它们。总之，与涉及身体鳞状和/或强鳍刺的物理威慑相比，crinotoxic 鱼类的化学威慑在避免捕食方面似乎要有效得多。