The more plants and decorations the better.... that is KEY
Having sisters from the same spawn usually helps.... but you can use unrelated girls
Knowing the girls!!! thats a key!
You want to release the least aggressive (the most mellow) girl first, wait a fw minutes then release everyone else in twos (since Im guessing you only have two hands, lol)
Keep an eye on them.... chasing is okay... a bit of biting or fighting is okay.... but if you see two girls full on out fighting (you can tell, they really go after each other) seperate them (I used my hand to block them)
If they kep going seperate one (the more aggressive of the two)
There will be a few nipped fins
for your tanks, 5 would be best as it will spread aggression better
I found it easier that I floated all 7 of my girls in plastic cups (so they could see each other) for a few days and fed them a small amount right before releasing them (mid-day snack)
Here are ALL of my girls during feeding
Ender and Merle are sisters
Dragon, Peanut, Eurydice, and Omen are sisters
and Anchovy is my "third- wheel"... a sympathy Walmart purchase that turned into an AWESOME sorority girl
And the tank: