I agree with Vitaly...
The novelty of watching fish in thier natural predatory mode is cool until you think..Gee my fish is probably going to end up sick with who knows ich, Hole in the Head..etc.., Fish in the wild have varied diets, believe it or not they don't just eat fish. Pellets will provide the staple for these fish to be healthy and colorful..supplement with beefheart, bloodworms, earthworm and if you need to watch something die feed it a crayfish, blackworms or earthworms.
Feeders are for rookies...Instead of feeding dogs healthy nutritous dog food I guess we should let them hunt down racoons, birds and squirrels..cuz they will eat it...we'll just hope there food isn't infected with rabies or worms right?