I've tried keeping many things with discus (eels, small cichlids, tetra, stingray, chocolate cichlid, uaru, rainbowfish, killifish). They are too iffy and scary. I love them but they can be dumb sometimes the way the scare so easily. Ultimately, you'll end up with just a discus tank so don't bother mixing unless you want to go through all of the changes. I even took the small tetras out because they would let them eat there fry.