NFC: New Fish

Since I'm still new to this, today was only the second time I went fish collecting. One method of dip netting, I have read about in the NFC articles, is running the net through dead leaves and small branches, which did work, I came up with two fish, a 2" Tessellated darter, and a small catfish, about an inch and a half. Thought maybe I had a Margined Madtom, but fairly sure it's a small bullhead. Caught another darter, and decided I had enough, since these are the fish, I hope, will get my tank to cycle. There is a small sunfish in the tank from my Sunday trip, he's probably not even an inch. Since they are all on the small side, and the tank is 38 gallons I don't think I have to many fish to start. The catfish is a pretty cool little fish, but when I put him in the tank he stays at the top in one of the corners, I thought he would do what the darters did, which was go straight to the bottom. Is he acting normal? I shut the light to the tank off. And will he,at this stage, eat flake food, I would hate to loose him. Will the darters eat flake food too, or is that really pushing it?