For bluecats and channels Im all for having the river up and muddy with water temps in the mid 40s. Oh yeah rippin current!!! As for Flatheads I guess I don't have such a perfect answer since Ive not really pinpointed just flatheads on the ohio. Id say water temps in the 70s with mild current and water stained. As for Lake fishin for flatties Ive done really well for prespawn flatties when water was clear to stained. Lets here some answers fellas. Maybe even give some reasons why you have that answer. my simple answer is thats when I seem to catch the most fish.