Hand feed fish is indeed fun. That is probably the highest level of interaction with them. You are the first one mention this can cause problem for tank maintenance when the fish associated your hands with food. I'll take a note of them.
No need to feel bad for the feeders. It is the way of life in the wild too. Big fish eat small fish, small fish eat small shrimps. Without this chain, there can be bigger problem. Many large fish keepers feed their fish live fish as food. Even some keepers of smaller fish would feed extra fry to their other fish. You know most fish would eat their own fry. It is the way of life. No need to feel bad about it.
When you mention "mutant fairy cichlids", that sound a lot like blood parrot. It is a crossbreed of several different cichlids species, their mouth can't close either due to deformation.
Most fish can have the habit of associate your presence with food. Since you have to be there to feed them. If the fish tank isn't at a busy location, the fish will follow whoever pass the tank, because they would think it is feeding them when a human show up.
Yep, they have their own little mind.
