depends on the size of the discus. neon's often become expensive snacks as they are a natural food for discus. cardinals do better as they can take the temps of discus tanks better than neons. rummy nose tetras are another popular choice. I wanted something a bit different for my wilds so I added 25 lemon tetras. once you get them out of the lfs tank they are quite beautiful and stay schooled most of the time.