Please help id this disease. Just took the koi out of the pond today and put him a 15 gallon with filter, no carbon and started treatment with Aquarium Pharmaceuticals Melafix and stress coat.
Thank you
Wow.. that looks initially to be a case of furunculosis, but usually the wound margins show much more red (bloody). That fish looks as though it's partially been cooked. (Good pix)
I hate to say it, but often these things have been acting internally long before you see outward signs. I've never had any luck using Melafix for anything, certainly not for this disease. On wetwebmedia.com there should be some good information for treatment, which would likely include furazone or nitrofurazone and salt (non-iodized) at low levels (you can use rock salt).
