5 of mines were good until reached sexual maturity.
Now I have 2 pair and one single female. The pairs often flair and tail beating each other, but nothing crazy, they rarely engage in real fighting. Most of the time they swim together, all 5 of them, unless one of the pair protecting the eggs or fry.
They not aggressive towards non cichlid dither fish, but were aggressive when kept with Thorichtys Helleri, even when were young.
Interesting thing to mention:
My both male similar sized, around 7". When lights is off one guy in charge, when lights is on, another. They love the same corner and each of the pair hang there and protecting in different time of the day. Weird