I have been experimenting with several species from the wild. There are many more forage fish than just fatheads and golden shiners. The brassy minnow seems to be more of a stream fish but a couple sources I read said they will adapt to pond life... I couldn't find any info on their spawning habits. That is usually the limiting factor for most forage fish in ponds, a lack of suitable spawning requirements. Are you sure the species you are catching is the brassy minnow? There are several other more common species that look similar to them in Iowa? Could you take a picture of a few and post them on here? I'd love to see some!