Not sure how big your tank is, but my pair bred in a 600l tank with a number of other fish in with them at the time. Admittedly, I never got past wrigglers with them, as I wasn't interested in trying to find homes for dozens of baby Oscars, but the aggression they showed towards the other fish was limited to keeping them away from their spawning rock. They took over maybe a quarter of the tank and pretty much kept to that part of it while they had eggs in the tank. That's just my experience, but I found my Oscars to be far less aggressive when spawning than Cons or my Sev pairs.