As long as the fish you catch for your tank are within the size limits it's legal. Which means no 3" bass but small bluegills-cats are fine.

Over the years I've had channel, bullhead and flathead catfish, gar and most of the sunfish along with darters and shiners, ect.

To me the pumpkin seed are the most colorful of the native fish along with darters and emerald shiners 2 pair or a male and a couple of females should work good in a 55. Any of the sunfish will keep similar to central/south american cichlids.

They aren't any dirtier than any other fish but most people feed them live food and overfeed them at that. Every other or every third day is fine and only as much food as they can eat in 30-90 seconds. Any leftover food needs to be removed. I've never had any trouble getting sunfish to eat pellets, although darters need live or frozen food.