oscars?

Oscars will often tolerate smaller, less aggressive fish if the are raised
together from the time an Oscar is as small as the other fish. I had an
Oscar who adored the sailfin mollie he was raised in the tank with but ate
any other mollies that were introduced after he had attained a decent size.
It also depends on the personality of the particular Oscar. Some will put up
with these unorthodox tankmates and some will go on a feeding frenzy. You
just have to try it and see.