lukifell - Is there any way you can get some closeup pictures of these adults? Lots of "talented", knowledgable and educated people along the southern Lake Erie shoreline and probably other places have tried to get emerald shiners to reproduce in ponds. Your location and conditions may be unique.
If you can send or post a picture (digital or film photo) of these fish, I would really like to see them up close. If they look good, I would like to see a couple specimens for some specific counts and meaurements to verify taxonomic features. I would send you a collection bottle and shipping box.