I had my betta's breed once, it was really awesome and at first scary it went a little something like this. I had them in 2 small tanks side by side, the male always flared up and tried to get through the glass to the female. My female was really fat with eggs and was swimming head down (I sign of submission I believe). I saw the male had made a bubble pile at the top corner one day, looked online saw it was a nest so I put her in with him. AHHHHHHH he killed her!!!!! He wrapped his body around hers and shook, then they both float lifeless...did they both die? Oh wait he's moving good at leat he lived, what the heck is he eating, and why does he keep swimming top to bottom. 20-30 secs later oh god, SHE"S ALIVE, wait she's eating stuff to and swimming up and down to. *I look closer they are putting little white balls up in the bubble nest. Ok, they stopped, that was scary....OH GOD HE'S KILLING HER AGAIN!!!! I soon realized they were mating, and they mated for hours, and hours, and hours. When done, he really did want to kill her.