Q: I thought it was safe to keep females together.  I recently acquired a female betta and I put her in my female community tank.  In less than 1 hour, 3 females were torn to shreds and there is plenty of hiding space. 

Question submitted by Michael, Manchester - Connecticut

A: OK, I'm missing the "?" in the above submission. As in ' what was the question?' :). So I'll fill in the blanks and add this sentence: "So is it safe or is it not safe to put female bettas together?". Since your submission got picked by the Gods of Randomness ;) and since you are bringing up and interesting topic, I figured I would not disqualify you for not 'really' asking a question and address the issue.

There are a few facts to learn about female bettas (most of which can also be applied to female humans LOL. 

bulletEach female betta has its own personality and own behavior. Some are very gentle and submissive, while some are real dragons. 
bulletIf females are from the same spawn, they are likely to get along fine in one community tank. That is because the pecking order has already been established and the fish "know each other". They are, after all, sisters.
bulletThe older a female the more nasty she may get (hehehehe). An older female is more likely to assert herself in the world ;).
bulletMature females which do not know each other (not raised together) will seek to establish dominance. One of them will assert herself as the Alpha female and all the others will have to yield to her. 
bulletEvery time you add a new fish, the alpha dominance has to be reevaluated and reestablished.
bulletIf you add an old grumpy dragon of a female to your tank, she is likely to challenge the previous alpha female. In the process she might attack everyone else. 
bulletIf you remove a female from your tank, and she happened to be the alpha female, you might end up again with torn fins as the remainder of the females will once again fight for alpha position.
bulletDominant female bettas do not like being ignored by males while in the spawning tank. If the male does not assert himself pronto and does not court them aggressively, they will SHRED him (aka give him a good old haircut)
bulletSome female bettas are so dominant they will kick the male's you know what during spawning, even if he is courting them as best as he can. (girl power! LOL)
bulletDominant female bettas also flare and display to each other or to males
bulletDominance doe snot have anything to do with size, as small females can also be very aggressive. But a larger female will be able to throw more wait around hence might win alpha position with more ease. Hence beware of older larger females!
bulletA female that came from a community tank is more likely to accept tank mates than one that was jarred. If jarred (living alone), all bettas become very territorial and then have a hard time "living with someone" again. (reminds you of any of you Xs?) LOL.

In closing, it is obvious to me you got a very dominant female that completely destroyed the established balance and harmony of your harem. I bet she was fully matured, possibly on the large side. Such a tyrant will chase other bettas around even if you have some plants. Although in time the chaos might subside, some of your females might by then be too hurt to fully recover (or even die from too much trauma & wounds). 

So is it safe to have female bettas together? If they were raised together, yes. If they are young and of similar size, probably. If they are of different strains, different age and different sizes, not always. When adding a new female, always keep a very close eye on your tank for a few days to see how it goes. If the new female is a trouble maker, place her in a betta display inside the tank. This way she is in there but unable to get to the rest of the peaceful population. A little pecking is OK, but too much pecking is dangerous. So caution is always a MUST! I hope this helps all of you make sound female accommodations decisions.