Peet, I like to freeze my guppies in an ice cube tray- a few guppies per cube. That way I always have them on hand, and dont have to take care of them. I just slowly thaw them out in cold water, since fish spoils easily.

My infernalis has now taken 2 consecutive meals of guppy-scented extra small pinkies. I havent actually given him a real fish yet, but he sure goes for the guppy smell.