Fish choose appropriately when and with whom to collaborate.
Collaborative abilities are integral to human society [1] and their evolutionary origins are of great interest. Chimpanzees are capable of determining appropriately when and with whom to collaborate in a rope-pull experiment [2]--the only non-human species known to possess both abilities. Chimpanzees are thought to share these abilities with humans as a result of common ancestry [2]. Here, we show that a fish--the coral trout Plectropomus leopardus--has partner-choice abilities comparable to those of chimpanzees in the context of its collaborative hunting relationship with moray eels [3]. Using experiments analogous to those performed on chimpanzees [2], but modified to be ecologically relevant to trout, we showed that trout recruit a moray collaborator more often when the situation requires it and quickly learn to choose the more effective individual collaborator. Thus, these collaborative abilities are not specific to apes and may be more closely linked to ecological need [4] than brain size or relatedness to humans.