Sitting in the boat tonight I had fish slurping mayfly bodies off the surface all around me. So when curiousity (read as bored) got to me, I dug out the spotlight and zeroed in one fish that was milling a few feet away for several minutes. Much to my surprise it was a channel cat. And there were a LOT of channel cats it turned out. Nothing very large, maybe 2 pounders, but they were literally everywhere for nearly two hours gorging themselves.
I even tried to tempt them with a crawler below a very short slip bobber to no avail. They simply were intent on eating the mayflies. Maybe I should carry some spent wings and an adjust-a-bubble for nights like this.