This isn't a betta (its a honey gourami), but I wanted to post....
I don't know what happened. I was about to go to bed, and I saw Fury gasping at the bottom of the tank. I thought she was dead. I put her into quarentine for the night, but woke up to her dead. :( I had the water lowered so she could breathe easier, but I guess it wasn't enough. I had a feeling she was going to pass once I found her gasping. She has a tankmate, a dwarf gourami. The dwarf gourami (Ghost) is fine. So I don't know what happened.
She will be missed.
RIP Fury <3