I have a 125 gallon tank, running smoothly for over 2 years with a single tiger Oscar, approx 8 inches.

I have been offered an 8 inch albino Tiger Oscar by a friend who is hospitalized and can no longer care for it.

Both fish are healthy, well fed and cared for etc...

I need to know some suggestions as to how to go about adding /introduceing new Oscar to current Oscar. Any suggestions would be appreciated.

Hi and welcome to OFL!
I'm no expert but I think it comes down to this:
If it's 2 males, they can be or become very territorial and aggressive.
If it's a male and female, a couple could be established.
If it's 2 females, things could work out.
I think it's allways a guess and I've heard a lot of stories where the new fish got bullied and had to be removed later.
Have you got any opportunities to rehome the new fish if trouble should start?
The others here will have more ideas soon!

Some oscars get tank proud and will not accept any new oscars, others are ok.

What i would do if i was you would be to get a divider just in case. Then add the new fish and see what happens. If one fish gets badly injured from fighting then separate them with the divider. If you have to do this leave them like this until all are healed and then put the aggressive fish into the other side. If the weaker fish still gets injured them rehome. If they are ok after 3 days or so remove the divider

there would be no assurance it would work perfectly but you can only
see that if you try. just be ready with a divider just in case. having
a bigger tank like yours is an additional factor it will work.

just wondering??? how come 8 inches only for two years, alone?
see my 6 month old blind oscar at 7.5 inches more or less

no doubt paul! mines not even a year and a half and its 11"

Update: introduced the albino into the tank: seems to be ok. Had the divider in all night. I removed it a short while ago and we're having some scuffles, stand-offs, etc...

I'm sure this is natural behaviour, but how long should I let it continue before giving up on having a peaceful life for them both in the same tank?

ADD: not sure why they are that size...both are healthy and well fed.

I think things may get a little rough but should give not much more than a couple of cuts and bruises, which will heal quickly, when waterquality is good.
If they don't get hurt badly, give it some more time.
just keep a close watch things don't get out of hand.

YAY!!!

It's been 2 weeks and we have removed the divider today, shifted things around in the tank and both seem to be getting along wonderfully.

Thanks to all for advice and input.

I'm so glad it is working out for you!!!

Just keep an eye on them for a while! And please post pics!!!

Im glad they are gettting on, keep an eye on them for a while to make sure they dont decide to start aggro

Well oscars are territorial so choose an oscar that is the same size or near that size