You're right, there aren't flatheads there. It sounds to me like you caught a white. White cats are kind of a dark gray, almost like a shark, on the side, and white on the bottom, with a broader head than a channel. And they don't have spots on the side like channels do. I'm almost positive there are only channels, bullheads, and whites in there. State record bullhead and white both came from that lake, BTW.