Well...first we'll look at the Clown Loach and Oscar together. Consider their growth rates. Oscars can grow fairly fast while the clown loach takes much longer to get to its potential size. So the clown loach very well could still be small when the oscar grows large....which makes it a possible meal.
Oscars generally do well with other SA/CA simi-aggressive/aggressive type cichlids. Of course you would have to have quite a large tank to hold more then just the oscar but some examples are Convicts, green terrors, possibly firemouths, possibly Jack Dempseys if you have the room, and red devils again if you have room.
Someone else from SC, nice.