If it's a babie oscar i can't see a problem, what the other's say is true, i managed to keep a full grown redtail black shark with my oscar's.......there's another member on here with two oscar's and a full grown redtail shark, but every oscar is soooo different, it's a case of trying and keeping an eye on thing's......some oscar's hate tank mate's, my old oscar's would be fine with anything, i even had my small senegal birchir at 4inch's with the oscar's without a problem, Iam not saying it would or would not work, unfortanatly with cichlid's of any kind it's a try and see thing, i know of someone who has a oscar/jack dempsey male/green terror male and a oscar all full grown for 3 year's in a 5ft/2ft/2ft.......busy i know but worked and all fine and healthy...