I have a 8" breeding pair that are usually separated due to male aggression. IME these fish can be VERY aggro. Good example...I have a 190, 10' long tank with a group of 7 Beani all the same size for the most part as the male Psittacus. EVERY tank he's been in he is the dominant fish and I had to move him yesterday to a new tank. They get BIG and are surprisingly mean for a fish not billed as overly aggressive. My previous pair the male was a solid 14" when I sold him. Watch out for the males aggression with the female.
ive had these guys for almost a year now, theyre a little over 12". The male does chase the female, but he doesnt seem to be harassing her too bad. She is left alone for the most part and her fins are barely damaged so no need for separation thus far. But I can agree that my big male is definitely the boss of the tank.