Good question I believe they are a blueish fat head minnow that come from lakes in minnesota. That I buy by the pound from RJ Hilger and sons, Antigo WI. I buy them small and medium sizes from one inch to about 4 inches long. As far as over populating Im not sure Its only been two breeding cycles and I am seeing 2 inch babies whereing stripes. I have hooked a small perch on a bass hook once trying to catch a bass in my other pond, and a twelve inch perch tried to swallow the injured fish right before my eyes. So im thinking they may cut down thier own population maybe if not I will. ha ha ha. Thanks for the question Chad.
