Oscars (Astronotus ocellatus ) are categorised as "New World" Cichlids they are found in the Rio Ucayali drainage & upper Amazon river of Peru and Brazil.
They are categorised as Aggressive and can grow up towards 14-15 inches.
You could probably get away with Jack Dempsey and some large Plecs.
You should be looking at a minimum of a 75G tank and remember an Oscar will attempt to eat anything that can physically fit in its mouth
Species can be kept with other cichlids as long as the tank is big enough and the fish are compatible in aggression and behavior, but you'll get the most out of them in species tanks. A mod will move this to the right section soon I'm sure.