I have a 125g aquarium and im debating on how to stock it.?

Well im not a beginner and I had my 55 gallon set up for more than a year. Well I just got this tank and it has began to cycle. My water has a natural high ph (8.4) but i've heard that most fish can adapt to such water conditions. Well I would like to have a pair of oscars and a couple tank mates. But the thing is the more I read the less I want oscars because I don't want one of them to kill the other when they get larger. I also would prefer to have a small group of catfish along with them. Also the tank is set up with driftwood, sand, few Anubius Nana plants, and normal lighting. What do you suggest?