I was told that they are Sculpin. I think there are lots of them as I see the heron catching them nearly everyday and have pics of cormorants catching them.
I thought they were bullheads when I looked closely at your photographs. Turns out they're the same fish just named differently where you are. They're found in both salt and fresh water which makes sense as I've seen herons with them on the shore and at our local reservoir.
Great catch....we have bullheads around our area too. I remember when we lived in Neenah and we fished by the dam.