you need at least 6 female betta to run a sorority. If you only have 2 in the tank then I would remove 1 until you can get at least 6 otherwise you will have a murder in the tank. You also need a min of a 10g tank and that would likely only support the 6 betta. Having the 6 females helps to spread out the aggression so one isn't being bullied to much. Also remember that not every female is suited to sorority life and if it is too aggressive it may have to be relocated. I have only had female betta in a tank with no other tank mates but my guess is the aggression would not transfer onto the cories
Last edited by Nothingness; 04-05-2013 at 04:30 PM.