The aquatic environment is full of tantalizing chemicals that can guide a fish to mates or meals. Now, scientists in Japan have identified the olfactory receptor and brain circuitry that picks up the scent of adenosine triphosphate, or ATP. Although mostly known for carrying energy within cells, ATP is also a constituent of fish prey such as brine shrimp and plankton. The newly identified receptor is unique to fish and amphibians and is the gateway to initiating foraging behaviors in the zebrafish.