i have found that when i use to feed my puffers live food it just made them more aggressive and they tend to "nip" at other fish more. plus i heard it wasnt good for saltwater fish to eat freshwater fish (i think it had more to do with my lionfish than a puffer) so i stopped feeding live fish. i did how ever feed them frozen silversides as a meat alternative to live fish. it got to the point that i fed mine the same time everyday so he got use to feeding time. when i would open the canopy to the tank he would start to spit water at me, b/c he as excited to get his food. also i would feed him, frozen clams, squid, silversides and shrimp pieces. he also would try and eat everything thing else i put in the tank for the other fish. the more diverse the food choices the happier your fish will be