I have a pond that I fish at which is 240 or so feet in diamater. One pipe leading in for drainage from storm drains and one leading outward to a parallel small pond across the street. The pond has a max depth of 28 feet and its shaped like a gradual sloped bowl. Its been their for over 20 years. My neighbor caught a 18in crappie there in the late 90's. He also stocked the pond with bass and pike last year and some crappie aswell. Whenever I go there I catch small green sunfish on the shore and I caught a baby crappie about the size of a comb with some corn. The pond is loaded with common carp. I can't seem to catch any crappie, bass, or pike there. I have tried almost everything from rubber worms to crankbaits, to spinners and more. Bread works for the gills and the carp same with corn. Tips? Here is a pic of the pond from fall.
And the baby crappie about 3-4 inches long http://i.imgur.com/aSIcaev.jpg
Do you have permission to place cover ? Also, past a certain point carp begin to actively hunt and eat other fish. If the population of carp are very dense it would explain the very few big pan fish and many very small 1s. A drawback of cover is it will allow many more of the juvenile crappies to survive. Crappie are NOT recommended in ponds or lake of less than 30 acres since they have a high survival rate and spawn young...Putting catfish in the pond might help...