Oscars are easy to raise and feed. It is usually best to start small with one to four 1-inch babies. The biggest consideration for the number of fish to house is tank size and filtration system. These fish thrive in most fresh water aquarium conditions, but like slightly warmer (76 to 80 degrees Fahrenheit) and slightly acidic (pH 6.5 to 7.5) water best. They grow very rapidly, will eat whenever food is offered, and produce more than the average amount of fish waste. A good filtration system, regular water changes and a large enough tank will help accommodate their size as they grow. It is not unusual to see an Oscar outgrow a 30-gallon tank in a year.
To learn more, read Choosing an Oscar