Myth: Male bettas can be kept with groups of female bettas.
Reality: Many pet stores suggest keeping a male betta with a small harem of females, and some betta keepers have tried this set-up with limited short term success. However, in the long run, such an arrangement almost always results in the injury or death of the females, male, or both; male and female bettas were not made to co-habitate outside of brief periods of mating and will aggress upon each other. Male bettas should never be kept with any member of their species.
Myth: A male and female betta can be housed together as mates in the same tank.
Reality: Bettas are a solitary species; they do not form mate bonds and thus will not recognize one another as companions. The only time one should attempt to place a breeding pair of bettas together is during the actual mating; a male and female betta housed one on one is asking for a massacre. Even with a careful introduction and supervised mating, injuries and deaths during reproduction are not uncommon. Male and female bettas simply should not be housed together, period.
Myth: Female bettas need other females for company and will become lonely and depressed without others of their kind.
Reality: Anthropomorphism is a grave enemy of fish. Bettas are a solitary species; they do not need companionship and will not become "lonely" or "sad" without the company of other bettas. Overall, other bettas simply create territory disputes and a need for a pecking order. Sorority tanks can be safely formed, but please understand that it is done for the owner's preference and not for the needs of the fish involved. Those wishing to keep social fish would be well advised to consider a schooling species instead of bettas.