So, this is a sort of post-facto thread, but the other day I woke up to find my betta fish dead. The morning before, he had ripped off most of his bottom fin and those dangly long fins, (pectorals?). There's nothing sharp in the tank, and it has live plants and a protected filter. I had successfully treated his slight fin rot on his tail fins the week before, and he was in great health. He had no history of tail biting.
So, my question is this: can tail biting to such an extreme cause death? Or was there some underlying disease that I'm not seeing? I was concerned that it might be the "betta plague," except that there was no real discoloration on his body (he was a blue-black-white marble halfmoon, I'd owned him since about Halloween).