Boy, that is unique. Sorry about Gambusia being invasive. What about Shiners? TFS? What do you intend to stock after the forage? I think Splake would be perfect, not many of my ponds have deep water fish, none to be exact. Except in the 100F plus Summer, most of my fish are hanging in the shallows, 8 feet and less. I used to hang out around Menomonie. Land of the displaced Norwegian. Chickens feet would freeze in the Winter and turn in club feet. Neat country, but those Winters, yikes. You could end up with an interesting and fun pond. Good luck!