Fishball7
Fish Fanatic
+1 what LadyDragon said. I have a strong impression that it is the bottles and small containers that house individual bettas next to each other from young and for long periods of time that exaggerate their aggression. Of course, generations of selective breeding enhanced their territorial instinct, but for a while now commercial bettas have been bred for show and they're mostly still so aggressive leads me to believe that how they grew up has become the primary factor to their behavior.
