Female bettas can only be placed with other female bettas if a various conditions are met. They have to be kept in teams of four or maybe more in an appropriately sized tank containing a lot of plants (silk or live) plus a lot of hiding places. Keeping greater than four female bettas together helps diffuse the aggression.
For boredom biters, there are a variety of things to do to enrich the betta's environment. There is little that can be done for bettas who bite to reduce the drag of their fins (halfmoons, deltas along with other long-finned bettas are particularly vulnerable go to this site
this), although reducing current in the river may help if the tank is filtered or aerated.
Temperatures which can be too low will lead to a compromised disease fighting capability leading to the likelihood of parasites and transmissions, slowed metabolism resulting in digestive problems and listlessness, and also other health problems.
During times of illness, it can be advisable to help keep their tanks bare-bottomed to be able to monitor their feces for quantity, color, and consistency. Keeping the tank bare also makes all the tank much easier to clean.
Bettas often patrol the tank. They will hang out within the plants for the while, then perform a quick swim throughout the whole tank, checking for intruders. Some bettas can't handle being in a community tank, in spite of the few betta-compatible tankmates, since they get so stressed and exhausted patrolling the tank.
Female bettas can only remain with other female bettas if a variety of conditions are met. They must be kept in categories of four or higher in an appropriately sized tank which has a lot of plants (silk or live) and a lot of hiding places. Keeping more than four female bettas together helps diffuse the aggression.