i brought my father to the pet store with me yesterday and while i was looking at bigger fish tanks he felt sorry for all the betta sitting on the shelf in the little bowls he dumped about 15 bowls into what he thought was a empty tank as i caught him dumping the last one i yelled dad no they will kill each other almost as soon as i said that a huge fish ( dont know what kind it was) came from behind a piece of drift wood in the tank and swallowed every last betta my father had dumped in the last ones tail hanging from his mouth for about 35 seconds i was so upset and my father felt horrible needless to say i think the betta would have been happier in there small cups and it cost us 2.99 a fish for every empty bowl.so im thinking in the wild these betta either will kill each other or be killed maybe it is a good thing we keep them in tanks!