GO FOR IT my friend has this set up of 3 discus, a silver aro, and a motoro looks awesome it covers top middle and bottom, go for it. Rays r generally calm and since they are picky i doubt that it will eat the discus just get some big discus first and get a small ray so they can go together and make the aro a little bigger than the ray jardni i dnt recommend as they are more agressing but they go well with rays all together. Just discus are ya. And no the temp in the tank will not be a problem for the aro even. discus 80-85 degrees same with motoro and aro 78-82 but i keep my tank at around 84 and he does just fine