Phylogenetically and morphologically close ambush piscivores can elicit different antipredatory responses in characid prey

A bstract Prey fish species can respond to the presence of predators using a variety of antipredatory behaviors to reduce their risk of being consumed. As such behaviors may also imply fitness costs, the ability of prey to perceive and appropriately respond to the predation threat is crucial to determine the persistence of its populations. Little is known whether antipredatory behaviors adopted by prey fish species are predator-specific or a general strategy employed regardless of predator species. Here, we used two phylogenetically close piscivorous fish species ( Hoplias sp. 2 and Hoplerythrinus unitaeniatus ) with similar morphology and foraging strategy (ambushing) to test whether prey ( Moenkhausia sanctaefilomenae and Astyanax lacustris ) behavioral responses were related to predator species identity. We video recorded and evaluated prey refuge use, habitat segregation, shoal formation, and mobility in microcosms before and after the addition of each predator. We found that M . sanctaefilomenae responded to the addition of Hoplias sp. 2 by reducing its mobility and keeping as far as possible from the predator location in a vigilant state, while shoal formation was employed regardless of predator species. On the other hand, A . lacustris had a consistent response to the presence of predators with no adjustment for predator species. We conclude that antipredatory responses may vary according to predator characteristics not obviously related to their morphology and foraging behavior, such as predator activity level and habitat use.