That size of tank isn't suitable even for a single oscar. They get huge, and are very messy, thusly they also should have at least 2x filtration of the normal sized tank for them. A single oscar could be kept in an 80gal tank for most of it's life, though I've seen people recommend putting them into 100gal for only a single specimen.
Thats not strictly true and 80G is very large (compared to many keepers for a single Oscar) . You could keep 1 Oscar in a 55G, with no tankmates so long as it is a deeper than normal (front to back tank). You can forget about keeping smaller fish in there, they will be killed in no time. I would reccomend some serious filtration somthing like 10X turnover per hour and even then you will need regular cleans and water changes. That said, the bigger the better!
As for keeping 2 there is no reason why not so long as you upgrade to 100G + before they get to 6". Some people dont agree with upgrading, though I have done it and my fish have always been happy and healthy.
Oscars are superb fish, one of my favorites but they require a great deal of care, are expensive to keep, need a large tank and really limit you in terms of adding other fish (hence why I have community tanks at the moment).
Have you tried www.oscarfish.com? I have been a member there for a long time and there are some very experienced Oscar keepers there.
Well done for asking first, best of luck whatever you decide.
So why spend hundreds of more dollars buying two tanks and letting them grow out of one...When you can just buy one large tank that will safely hold them?
So why spend hundreds of more dollars buying two tanks and letting them grow out of one...When you can just buy one large tank that will safely hold them?
I don't think it's unsafe to have 2 oscars in a 55G for a few months. But you are right, in ideal circumstances of course they should be in one tank for life.
In the case of my Oscar, for me it it was about giving the fish the best quality of life I could afford.
I could not afford a 55G + tank for my Oscar so I got a 40G while I saved up the rest of the cash. I actually ended up giving him to someone with a massive (100's of gallons) tank but the intention was to rehouse him myself. If you havn't guessed, in this instance I had fallen in to the trap of not researching Oscars first!
It worked out though which is my point, I got to enjoy and care for the fish which was happy and healthy even though it started life in tanks that were "too small"