I live in Mount Pleasant, MI. I fish primarily the Chippewa river. I've never seen anything like this before, and now I've seen three in the space of two days? What are these things? Anybody know? Sorry for the poor quality image. It was the best I could manage as it was swimming away. 

 

 

Looks like some sort of eel to me.

Really hard to tell with the bad photo, but looks like it could be an Eastern Hellbender. Although you’re a little North of their reported range. 

I saw a large dead one that looked like it had been chopped by a propeller on Keuka lake. That's a cold deep lake so if they can live there they can probably live in MI too.

Freshwater cod/ling?

Color pattern looks like a bowfin 

Might have found the answer...

 

I googled it... want nothing to do with those things man. Straight up sci-fi monster right there.

We filleted a bunch of walleye out of Lake St Clair and one of them was full of baby Lampreys. Nasty fish.  We catch a lot of fish with the bite marks from them.