I have a divided 10 gal
. There is a male betta on one side and a female on the other. There are also several dwarf frogs in there. The frogs have a little opening where they can go back and forth to each side. Yesterday the betta switched! Completely just traded sides! The opening isn't big enough for the male to fit through so I'm thinking he jumped. I really think though they planned it out just to weird me out! Haha!