I have had two Male Betta's in a small tank with a clear plastic wall in the middle. At first, they would act aggressive toward eachother. They have been in the divided tank for about 4 months. I thought that the way that they had been acting, that they maybe had gotten use to eachother being there. So I decided to put them together. They have been acting fine together. They swim together, and they rest beside eachother. I have seen them puff up only right when I first put them together, and now I have not seen any sign that they are unhappy being together. Is this possible? Can I keep them together, or will they kill eachother all of a sudden, without any sign?