Wow, so I don't know if anyone has ever done this before. But okay for awhile I've have my betta named Aurora in my big 55 gallon, and he absolutely just loves the huge tank. And I had another betta in a small tank. I noticed the other day that he was getting depressed and just not eating as much as he used to. So I thought...a huge 55 gallon tank, with lots of seperate areas to claim as your own..just maybe they'd be able to live in it together. So I put him in and watched of course for awhole day. And to my great surprise, they are living in it without fighting!
Once and awhile there were a few occassions where they met face to face and just flared their gills a little. But they never went after each other. And now its been way over a day and they are even going to the top and eating by each other without caring. Its amazing and awesome! I think they can do it because of how much space they have in the tank.
Please I hope no one bashes me or anything, but I tried it and so far its working brilliantly and they aren't fighting or trying to pick fights. They are just both living happily in there.