if "corydoras" work with geophagus/satanoperca...wouldn't pretty much any of them work? I know there is some minor variance in the size they reach but other than that aren't they pretty much the same?
Yeah I'd be a bit worried [long term] with some of the larger growing species of geophagus. I think Bderik lost a big altifrons because it got a small fish stuck in its mouth. With the smaller species of geo (or juvis/sub-adults) most corys should be fine, just separate them before the size difference gets too great.