As mentioned above, it's a bit of a crap shoot
You get all the gentle fish you want, then 1 dies before you can add the aggressive ones
Or you add everybody and are finally happy, then 1 dies
IME, I've just put up with the aggression that occurs when adding new fish
I built an acclimation box that is pretty large compared to what you can buy from the LFS, and it didn't help much. All it did was freak out the existing fish when I opened up the bottom hatch to let out the captives ... the residents swam into it and got trapped 'cause they were too stoopid to find their way back out
