Generally no.
I have seen a 180G with a pair of maroons and a pair of percs (along with a whole bunch of bta's), but as I understand it, this is the exception to the rule. It's very risky to try, but apparently possible. I wouldn't suggest trying it, much more likely to end up with some very beat up or dead clowns IMO.
Maybe someone else has more info?
Edit; Oh yea, I think pinkskunk had pinkskunks and some other clowns, but I think that was a 5 or 6 foot tank.