You may luck out if you keep the discus well fed and keep plenty of hiding spots for the shrimp. Everyone told me that my RCS would never last in my 90g, as the clown loaches would surely eat them. None of the 3 clowns even bothers them. I've seen the shrimp swim right by the mouth and they don't even bat an eye. Cichlids, admittedly, are a little different. It may be doable, but do you really want to risk it?