We have had a slow water line leak for 2 years now, making our yard very wet and spongy. While digging to find the problem and check over areas, we found these in some wet-ish, dark places. There were at least 30.
St. Clair County Michigan fish
I've consulted with a few of my fishery colleagues and they think it looks like a central mudminnow – a very hardy fish that has the ability to breathe air.
Thank you for the response. That does resemble it. However, none of the ones that I saw had the fin on their backs.
You're welcome. The fin is not always visible but at least 6 fisheries biologists concurred that it is a mud minnow.