Not all catfish are bottom feeders. Some are predators. I've caught blues and channel cats on bass lures, in cold, running blue water. My grandpa used to do bottle sets on backwater lakes--- the trick is to hang the bait several feet above the anchor weights. Use the right bait, 'cause if they'll hit minnows they're probably not bottom feeders. If you're really worried about it, buy farm raised fish. They used to feed them whole kernel corn, and the fish surface to eat it. Probably fed on some kind of grain (wheat, which is not wheat anymore) these days.
Thin sliced, breaded, fried, with a little Tabasco--- country boy heaven!