yeah, gonna agree with the guy above. a pet store will sell you any fish if you tell them you want a fish. They'll sell you a feeder fish as a pet and say "oh it will do fine with an oscar" if it makes the sale.
and like the guy above me said, what size is the tank... how many other fish are we talking about?
If you have a large tank with plenty of plants... you could do well with pink kissing gouramis, clown loaches, Convicts... I had a friend who housed clown loaches and convicts with the oscars and it worked well.
basically... you will do well to avoid any fish small enough to go into its mouth and more aggressive than the Oscar.
but it depends on how many fish you have now and the current size of the tank. Aggressive fish need plenty of territory to keep from attacking each other.
it also depends on the type of "other aggressive" fish you have. Some fish are just not compatible, so I don't feel comfortable recommending a Kissing Gourami if one of the other fish are its natural sworn enemy.
So we need more info. Type of fish, how many you have, and size of tank.
