I'm no purist, but I can tell you that it doesn't take many irresponsible
users of live bait to do some incredibly nasty bucket biology.

Gold fish are used for flat head catfish here since they eat live bait
instead of being scavengers like their cousin the blue cat. If you use
them in a contained lake or pond and they survive being bait, I would
think they could be a problem. I have always heard to never use them
unless it is on a river or some other running body of water. Whatever
difference that makes???? They all feed something.

I also don't like it when people release store bought minnows into a
lake or pond.

I guess that is why I use mostly game fish for bait.