A word of advice

[RandomWiktor]

I've noticed a ton of posts lately involving horror stories with female bettas. Some involved the inproper number, some involved male and female groups, but a surprising amount also involved perfectly acceptable groupings in adequate space. In light of this, I would like to humbly suggest - as I have in the past - to keep all bettas singly with no other fish. I realize everyone likes to see fish interacting, and have their tank better utilized by multiple animals, but my argument is this:
Captivity puts unnecesarry stress on fish, and as with all animals, stress effects behavior by either making the animal nuerotic and nervous, or agressive and irritable. I would like to suggest that perhaps some females who do not cope well with captivity become either overly submissive, and are attacked, or become overly agressive, and do the attacking. In the wild, male and female bettas alike would have adequate space and vegetation to get away and hide if other fish bullied them. While a 10 gallon tank is OK for passive females, there are simply sometimes very agressive females, or very submissive females. When a dramatic difference in dominant behavior arises, the underdog can not get away. She can hide, but sometimes hiding isn't enough when a group of muarading females is after her.
Bettas are a species that really only get together when it is time to mate. While they tollerate the presence of other fish, it still comes down to them being competition in an allready stressful situation. By placing females together, there will always be the risk of a vastly inbalanced heirarchy, resulting in fighting and death. I would suggest keeping males and females alike singly. The lessened stress will probably improve health and lifespan, will eliminate the risk of being hurt by other fish, and will end the heartbreak of finding your fish mauled and dead.
Just something to consider. I know many people who have happy community tanks will disagree, but for those who aren't sure if they want to take the risk, it is an option that should be considered.

 

[OohFeeshy]

I agree. Generally I've kept my bettas in the communtity until I have another tank for them. They are fine to start with, however, after a week or so they become aggressive. If bettas have been kept on their own at the shop, your advice especially applies.

 

[RandomWiktor]

Absolutely; most of the Wallmart girls, for example, are kept alone. I've had a few, and they are wildly agressive. I would dream of putting them in with anything, not even a snail or frog. My little girl Valkyrie flared at and harassed my snail. If she can't tollerate an invert. in her tank, how is she going to interact with other fish?
Which brings another point: please for the love of god, evaluate your females' behavior before trying them in a group. If you're at the store and she's the biggest fish in the tank and is flaring and chasing everyone around, she's probably healthy, but she's also probably going to kill your females. If you almost didn't see her because she was hiding under a rock, she'll probably get killed. Look for females who generally avoid one another, or solve problems with a quick flare rather than a quick nip.