I've got a dwarf puffer living in a 20 gallon with a clown pleco, a candy stripe goby, and a bunch of endler/guppy hybrids. He's been in there for months now and all I've been feeding him is frozen bloodworms and frozen brineshrimp and he seems to be doing fine. Are snails absolutely necessary? I've never fed him snails and none of my tanks have snails in them.