the betta hierarchy

[Donkey]

I have a 55 gallon tank (heavily dorcated with drift wood, moneywort, and stones to make caves) with a small female betta sorority of 5 girls (and two dwarf platies). All but 1 of the girls have been in this tank for about 3 weeks, the other 1 has been there for over 1.5 years. There is one female, slightly smaller than the rest and they absolutely refuse to allow her to join the group. They beat her up pretty bad and she stayed hidden for days. I eventually had to tear the tank apart to catch her. She is now in a breeder net and each morning she gets to eat a platy fry, this seems to be helping her look healthier. She was looking rough for a few days.

Anyways, do you think they will ever allow her to join? I'm thinking it's because she is smaller and weaker than the other 4 girls....what if I added two other small females at the same time to disperse aggression. None of my girls are aggressive towards eachother, and never have been. They just really don't like this little girl.

[Aiptasia]

Maybe, maybe not. I don't think it's too likely in the fish's current condition. Generally, when adding a new fish to an already established tank, you'd do well to re-arrange the tank and completely redecorate it to put all of the fish on an equal footing with regards to territories and borders within the tank. You might be able to get the fish to mix socially in this way, however if the other fish are "used" to one particular pecking order, any new fish is going to be low fish on the totem pole.