Need Illness Identification Assistance Please

[Desert Aquarium]

The wife mentioned lastnight after the tank was dark that she noticed something, I couldn't get a look until I got home from work today. Here is what is progressing:

 

[TerryB]

Looks like it could be fish rot. If the area is dark or black in color then it may be a species of Vibrio bacteria that utilize iron. I would probably try some Maracyn-Two at double strength in quaratine. Keep us posted.

Terry B

 

[Desert Aquarium]

Any idea what the cause would be? Tank wanter parameters haven't changed, and there have been no additions or deaths in the tank for months.

 

[TerryB]

Bacterial infections often start in injuries. Maybe it is the result of aggression. Do you add iron to the water at all? Do you use tap water or RO?

Terry B

 

[Desert Aquarium]

Last 40% change was with Distilled, Sodium free.

I use IO Salt.

No, I don't add iron. No real LFS, but this weekend I'm headed to LA and will stock up on supplies then