hi there,
Whereas we certainly don't want to alienate you from our website, I have to concur with the rest of our members. Oscars can grow very large indeed. I wish I could show you my Oscars in my 300 gallon tank, I think you would be openmouthed at how big they have got in less than two years. what type of filtration have you got? I appreciate that it might be difficult for you to give us detailed information, a good description would be a start. I'm just worried that once the Oscars start growing, you are not going to be able to keep your water in the condition that needs to be to keep Oscar's healthy. Unfortunately, oscars are not the hardiest of fish when kept in poor water conditions. Three adult Oscars in 60 gallons of water will not work, period. Even with good filtration, I doubt very much whether there is enough water to keep up with the amount of waste large fish like Oscars produce.
Anyway, I know that this is probably more negative than you wanted to hear, we are just here to help and advise people on how to keep their fish healthy in the long run.