I have it on good authority that they are present in impoundments in Ohio were there is a stream flowing in and/or an area of clean gravel or unsilted substrate for them to spawn on. I don't really know how that translates for the average pond owner. I suppose some configurations could work, whereas others may not. I'd love to find out if they would work for anyone. The idea being that they are large enough to not be wiped out and maybe at the same time provide some larger forage for larger predators as their offspring are growing to maturity. I'm new to the pond management thing, so I'm just throwing out ideas here.
