Well I will really be glade is anyone can tell me any other fishes that will be good to add to this tank. Recommend fishes that will not cause me any problems with the ones I have so far. I will research any fishes you will recommend right away
I honestly think you'd best off starting with a discus only tank and then adding fish IF you have the room and the discus' water conditions suit them. remember discus like VERY soft water, cardinals also like soft water and lower PH. For discus to breed the temp needs to be mid 80's so if you want them to breed, don't expect them to at lower temps. Discus need a lot of time and care, I honestly think you'd be best off keeping them on their own.
What filtration will you be using? As they are such large fish they can produce lots of waste and get stressed easily - meaning your nitrites can shoot up, especially if you are addig 6 at a time.