I have a single species pond of YP that is holding it's own as far as balance in my opinion. I excavated in 2008 and put fatheads minnows in the still muddy water in august of that year. In May of 2009 I put 200 yellow perch in I purchased as well as 90 or so fish I moved from another pond of mine, all were less than 5-6 inches. I hand feed usually twice a day weather and wind permitting. I had ten inch fish the following year. The only management I do is kill every fish caught under 5 inches, release any perch 12 inches or larger to keep my YOY predation at it's highest possible rate, and I eat 8-11 inch fish which are the nicest sized to clean anyway in my humble opinion. I still have minnows that can be observed in schools around the edge of the pond if you look hard enough, and I haven't had my pond stunt yet. I do find some floating fish annually that I cannot explain, found a dandy one pushing 16 inches this morning. I got a picture of it but been so long since I posted here I can't recall how to put it up here