However, in teleosts, the results depend on the species or strain of fish . For instance, the results of group size on aggression show alternative trends in four common species of ornamental fish . A complicated atmosphere reduced aggression or even led to cohabitation without combating in intruder–resident tests with the pearl cichlid Geophagus brasiliensis , whereas other cichlid species showed contrary results . In male bettas which are socially isolated at 6 weeks after hatching, the incidence of agonistic behaviors raises after the termination of mutual fights . Under normal rearing circumstances, whether in personal aquariums or in advertisement facilities, male bettas become distinguishable from ladies at 2 to 4 month after hatching and must be separated into individual containers to bypass accidents due to aggression . Females bettas are generally reared in communal tanks, even though, some women were reported to display fierce aggressiveness .