Ok for the last 2 years almost i've keep my 2 bettas in the same tank and they don't attack each other. And today i got another tank for my neon tetras and wanted to put the female betta in with them. When i removed the female betta the male started attacking the other fish and ended up killing my 3 balloon mollies. When i put the female back in he stopped attacking the fish and just stayed around her and didn't attack her or the other fish. Are my betta attached to each other or is something else going on? This has never happened to me in my 5 years of breeding and caring for bettas.