Identify disease?

Question

Betta Disease?   So, I wrote this whole thing out, but the darn thing somehow deleted it all. Therefore, i'm going to make this super short. Sorry.

I was wondering if you can identify what happened to my fish? She's already dead, but I guess you could say I want some closure.

She was fine last night, then this morning showed signs of some discoloration. I separated her so I could keep a closer eye on her. 5 hours later, she had progressed to the photo I attached below.

And completely off topic, I was also curious as to how you had a pet fish while in the Corps. I was always told they had a zero tolerance policy. Even if it was a fish.

Thank you.

Answer
Sarah,
I see from the picture that she had clamped fins. Have they been like that long or is it that is had just happened. Clamped fins can be a sign of stress and illness. I see another tail in the upper right hand corner. Is that another Betta? Did you have more than one in the same tank? She did have a severe case of fin rot. The major cause of fin rot is bad water quality. Are you doing water changes every week? Is there a heater in the tank? Remember, they are tropical and need their water to be at 80 degrees at all times. What were you feeding her? If you have another Betta just make sure you use a water conditioner when you do water changes, have a heater set at 80 degrees and make sure the tank is large enough.