Are you after algae eaters? (Which are the suggestions already made.)
Or were you after fish to eat any scraps of food the discus leave?
In which case, the algae eaters are great, some people have corys or even some rams can be good.
i've been searching for good CLEAN clean up fish too. Tried BN's and pleco's yes they are great at cleaning up scraps of BH and other food, but they make so much waste it isn't funny... i mean these guys are s***ting machines. The pleco's also barge into my plants pulling them out of the gravel . Anyone know any good, peaceful, discus compatible clean-up fish that produce less waste?