yea i have my oscar in with 5 clowns and a couple of balas and they get on fine.
oscars sometimes a lil amused as to what the clowns are doing but thats it.
oscars about 6" now and my clowns and bala are about 3".
I have to rain a little on your parade. Sorry. Bala Sharks need huge amounts of room, buddies, and swimming space. I've read that they need 150 gallon tanks and up. But, I think the (1) Oscar and several clown loaches would do just fine. not sure how many clown loaches would be good though.
at least four clowns to keep em happy