I have native fish in my 1800 gallon pond, pumpkinseeds (a sunfish) and blacknose dace (a minnow). I caught the pumpkinseeds on hook and line and the dace with a seine, both from a creek near me. The pumpkinseeds have done very well and seemed to easily adapt to the pond, and have even spawned. I caught them two years ago, and while I have only seen 4 of the six so far this spring after our very hard winter, it is still early yet. I caught them as adults two years ago and their life span is about eight years, so I wouldn't be suprised to lose one every once in a while. The dace did not fare as well, as I think they are more adapted to moving water. I put fifteen or twenty in two years ago and as of last fall only had two or three left. I may try to replace them this year with one of the shiner species.
The only caution I would have is that my natives are finicky eaters. The pumpkinseeds will not eat flake or pellet food, so I have to feed them chopped up raw shrimp (which they love!), bits of raw ground beef (although there are two of them that will not eat the beef), and live meal worms that I get at the pet store. I only feed them three or four times a week and meal time is very entertaining as they line up and wait for me to throw a piece of food in. They are very competetive at feeding time but otherwise seem to get along well in the pond.
I suppose keeping a wild carp would be like keeping koi, but I do know that some catfish can be quite agressive. You may want to stay with one of the smaller species like a bullhead. Good luck with your pond!
Phil