If youre going to do discus, I would keep them by themselves. They need pristine water, and dont like most other tankmates. Maybe a pleco to keep the algae under control, but make sure he doesnt suck on your discus (Ive heard of that happening). My aro got along well with the discus as well, but he was too aggressive during feeding and would aggitate the discus. Just if I were you, Id start with 6 to 9 or so in a barebottom, feed them till theyre fat as hell, wait till two pair off and sell the rest. Or try it with a random assortment, but discus are their own worst enemy, so you never know. Definetly the most beautiful freshwater fish out there in my opinion though.