Ok, i've looked everywhere online, and can't find an example of a "yellowfin topminnow"...dang fish ID book may have led me astray....although i can't ID it for certain, the tiny minnow looks like this:
http://pond.dnr.cornell.edu/nyfish/Cyprinidae/lake_chub.htmlwith one exception, the main tail fin (excuse the layman's terms) is broader than that, and extends around the tail, like a beta fish, connecting the Adipose fin and the anal fin. It honestly looks like a topminnow, but the only ones of those i find online are tropical, lol...and i don't think a beta fish would survive the winters.
edit-
this is fairly accurate, just more brightly yellow, and without the spots (that i can remember).
http://www.bio.txstate.edu/~tbonner/txfishes/fundulus%20notatus.htm