We've got 2 female chocs around 7" in a 6x2x2 in the house with a pair of rotkeil 4 deamon and theres no aggression between the chocs or towards any tank mates, they are so placid but will stand up for themselves if they need to but as of yet ive never seen them start anything.
As for the nuechal hump ive no idea as i could not tell you the difference between our breeding pair as they both look alike so far.
The breeding pair are wild caught fish and their colours are amazing compared to the two females we have and they always showed a much more intense colour from no size.