I have a "pair" of adult Blue Dempseys (both blue) in a 125 Gal with a breeding colony of 25+ Steiny Geos and a few other Cichlids... The Blue Dempseys easily rule the tank...
Althuogh, As Juvis, I baby my Blue Dempseys and would not force them to compete with other fish. Blue Dempseys are prone to parasitic illness therefore I do what I can to reduce their stress so they can beat the odds of parasitic infection...
That being said... I do have a group of Blue Dempsey fry growing out with slightly larger Steiny Geo fry... So far they are fine together, but the first sign of aggression I see from the Geo fry to the Blue fry, the Geos become food for someone else...