Can this work? I have a 15" silver that has had all sorts of tankmates (p. bass, silver dollars, gar, stingray, dat, etc.) with no signs of aggression. But I have never kept it with any other aros, esp. a smaller one. The tank is 6'L x 28"H x 24"D.
You can try. Only about a one in three chance of it working, so you need to have away to separate the two aros if they fight.
Your tank seems pretty well stocked with soon to be monsters, though sizes of the other fish are not listed. Are you sure you have room for another potential monster fish?