my tank consists of 3 yellows, 3 empresses, 3 orange peacocks, maybe 5 lumpheads (juveniles they hide a lot) 1 adult and about 7ish juvenile red jewels, 1 dem, 2 HUGE electric blues, 3 white and 3 striped convicts (<3 mystic) and 2 baby golden spot plecos
they all get along fine, they have their moments - lil dem been chasing the striped convicts around and male empress has his moments at nipping at the tails of the 10 times his size electric blues (lol)
[edit] oh and 4 juvenile kribs (that I have seen)
there are rules to be followed but my personal feelings are how you maintain the tank - I totally reorganize all the rocks/caves when introducing new fish (after letting them float in a bag for a while) - lots of plants, driftwood etc
with the dems as they say ya need at least 12 to stop them killing each other - so I'm sticking with one(for now) - he seems really happy
to me it is all about providing enough hiding places and areas for territory