I dont see why not even later in life. I have 3 9" O's in with an 8" Orino and a 13" Pleiozona. No issues in my tank. I'm sure lil guys will get along as well.
Sweet, I acquired a Oscar from someone who didn't want it, so I have it in a 55g right now but id like to put it in my 120g grow out. 2 bass in there right now.