Imagine Mom, dad, big brother, sister and several generations as much as 7 generations plus the other fry from the brothers and sisters a complete harem living in a tank in a family harem you plop a different specie of fish that may eat all the fry and younger siblings or a complete reverse where the colony decides they want to pack up and target the intruder that for the life of it can not get away so it pines away in a corner or the top of the tank, maybe the intruder stays at the top corner til it comes down with a disease from stress and all of the sudden your whole colony is wiped out due to a disease explosion.. The site of a majestic family harem is a site to behold and is so fascinating I really wouldn't do it..
I had several 20gal longs at one time in my hobby and i had a tank full of Multi's at one time and the aggression that these tiny gangsters have is amazing.. Good luck my friend..