I use to fish down south and these sure do look like the Warmouth we use to catch down there. The DNR tells me a true warmouth will not survive the cold water this far North.
I believe you are correct.
According to the Wikipedia, more common in the south but are found as far north as Canada.
“Warmouth are found throughout much of the south in the Mississippi River drainage, from the Gulf and Atlantic coasts and northward to the Chesapeake Bay, and westward throughout Texas to the Rio Grande, and northward into the Great Lakes basin area.[3][4] The warmouth is a highly aggressive and hardy fish, and they can live in ponds, lakes, rivers, and backwater streams and can often survive in streams with low oxygen levels where other species of sunfish cannot. The species exists with breeding populations in southern portions of Canada, and likely has existed there for many years prior to being detected.”