Hi Armadillo
I dont know if the otos would bother the Discus during breeding. Most likely the Discus would bother the otos, protecting the eggs and fry. I really dont know since Ive never raised any fry yet.
So thought Id just stay on the safe side, keep the tank cycled for the 'just in case' should happen. Keep no other fish with them when the time comes and see if I cannot raise some Discus fry. Sure would be nice. ... But I know that I have no experience in that field so no telling what may happen or NOT happen.

~ kate