Well some of you know I had exodons aka satan fish, in my tank that I had to get rid of. When I first got them they weren't so aggressive but yesterday they had a massive freak out and were attacking each other and my oscars. Fortunately I found a great home for them with more exodons to hang with. Since they've been removed from my tank my oscars seem much more active and happier. I have 2 red belly pirrahnas as well, I planned on keeping them as well, but a friend of mine had 2 red bellys that just passed. I know I just got mine, but I offered him my 2 little ones because he knows and loves red bellys more than I do. Soooo long story short my tank now consists of 4 oscars, 2 smaller chiclids, and the newest part of the family, a round body green terror. Here's some more crazy news, those 2 small chiclids I got, that I thought were south american, are actually african chiclids. I know some people frown on mixing africans and s. Americans together, but to be honest my oscars are in love with those little guys. Hopefully it won't change when they get bigger! And last but not least that 85 gallon I have, turns out to be a 110 gallon. I measured dimentions of the tank and compared to online and in stores and I found a tank like mine with the same measurements that turned out to be a 110. So people give me a yes or no, my local shop quoted me 1100 usd for a 180 gal, and stand. Will that be good enough for just my 4 oscars? I know I ask this a lot with tank size but please bear with me. I'm new to this aqarium thing and from the impression I get is, I need more tanks, because more tanks are fun, I have to have every fish, and my pockets no longer have money in them! Its fun, but very stressfull at the same time. My little oscars and I have a bond goin on now, they are like little puppy dogs when I walk in the room, they get off the bottom and swim at the glass doin their little dance, its hilarious.

with alot of proper filtration you can get by with it.

the problem you run into with four oscars is a dominance thing in a 180. in a 6 foot tank there is really no where to hid from the dominate male fish so if you have a subdominate male as well then the fur will fly so to speak.
oscars are best kept in pairs of in groups of 6 or more to spread out aggression. and needless to say 6 oscar will require a very large tank.

I run a 180Gl for my Oscar and kept a big Vieja with him.
It looked great at first, but in the end the territory was still too small for 2 big ciclids. I had to remove to vieja, for she started beating up and biting my Oscar.
Now my O's the only "fat" fish in the tank and he's shown incredible change in behavior.
If 2 O's get along a 180Gl wouldt be nice.
adding more fish will give a big chance of trouble due to aggression and boiload as well.
The Boss has 4 O's in a 300Gl and they seems happy,but, man, that's a huge tank.