I feed mine bloodworms, and occasionally brine shrimp. I also have some frozen krill, though I haven't tried it yet. I have three planted tanks in addition to the puffer tank, so I have lots of snails. I've been picking the snails out of my tanks and dropping them in for the puffers. I haven't seen them eating them, but I do see empty shells around, so I assume they are hunting them. I only feed bloodworms a few times a week, so they will keep up hunting the snails.