Theoretical models predict that modalities of prey detection depend upon foraging modes: ambush foragers will rely on visual cues to launch a strike whereas active searchers will use chemical cues to locate prey. Testing this prediction is hampered by phylogenetic conservatism; ideally, we need to compare closely related animals that differ in foraging mode. Aquatic filesnakes from tropical Australia offer a unique opportunity of this kind, because female filesnakes ambush large fish in deep water whereas male filesnakes search actively for smaller fish in shallow water. We exposed freshly captured filesnakes to artificial prey items providing visual and/or chemical cues and measured tongue-flick rates and feeding responses of the snakes. Males responded most intensely to fish scent, regardless of movement, whereas females responded strongly to movement. Thus, our data provide the first intraspecific (sex-based) evidence for a functional relationship between foraging mode and the types of cues used for prey detection.