Oscar tankmates?

Thanks for your answer to my question about putting two Oscars together.

I don't want to risk having babies, though, so I suppose I'd rather not. I'd also rather not risk getting two males that will fight all the time.

Now, for a tankmate for my Oscar, I'd like to get a fish with an equally large mouth. I like Jack Dempseys and Green Terrors, but their mouths are tiny, in typical fish fashion, so I was thinking of perhaps getting a Jaguar Cichlid. Would that make a good tankmate for an Oscar?

Do you know of any other fish with large mouths that would do well with an Oscar?

Actually, I'm more concerned with one Oscar beating up the other one a lot. And I'm concerned that I'll end up with babies, which I'd rather not have.

Of course, I love Oscars immensely, so maybe I'll just break down and get two afterall.

But I'd still prefer right now to get another fish with a big mouth to keep him company. That's on top of my Pleco for algae eating and bottom feeding.

Well, the tank will be, at first, a 20 gallon, but within 3 to 4 months, the aim is to have a tank no smaller than 75 gallons and likely more like 90 gallons.

I only want three fish in there, as I want them to grow to their full potential.

One will be my red tiger Oscar, the other will be a Pleco or maybe one of the smaller varieties if I can find one as long as it still eats algae. The third, I dunno.

My criteria would be that it MUST be from South America, as I'm trying to create a South America tank, with somewhat acidic and soft water.

And, of course, it has to be able to co-exist with an Oscar and a Pleco. Niether kill him or be killed by him.

And, finally, I'd prefer if the third fish was a little smaller than the Oscar. Maybe 8 to 10 inches at full size. Just to fully show off the Oscar's size and allow it to grow to its maximum potential.

Perhaps I will get a fourth fish later on, but it will be a bottom feeding catfish, or maybe some form of South American crustacean(if one exists).

Any help would be appreciated?