I fish in a friend's 15 acre stream fed pond. He stocked Bluegill, LM Bass and catfish. It also has a healthy population of Flier bream that were native in the stream.
To my delight it has some really nice Black Crappie too, but he didn't stock them. He suspects someone put them in as opposed to them being natural in the stream. I'm just glad they are there.
Did you stock the Crappie? They look plenty healthy.