The trick is to get a compatible pair.
Best option, buy 6 or so fish and put them in a 90gal tank. While they are growing, search for places to sell 4 X 1/2 grown Oscars. Watch the fish, you will see when a pair form up. Sell off the rest.
Then just look after the pair and let them do their thing.
Next problem, what do you do with 50 baby Oscars?
Ian