My betta has lost his fin in that back there was a female betta with him at the time.?

Question

I think she bit him

the male betta was fine a couple of days ago happy and eating now he just stays at the top of the tank not moving he is a red fish but the part missing is white

Answer 1

It's possible but not likely. The males are usually the more aggressive of the two. I would suspect you are dealing with a bacterial infection but I would need to know much more about how the fish looks and acts before I could really help you with this.

MM