Finally got up to temperature, currently 18.6 and was thinking the dermo looked less angry, but having got the patient out today to inspect and decide to treat or not, found one blister had burst and the other still strong, do had to act.
As this is my first real attempt of this sort I am still not sure how successful the procedure will be and looking at the damage the dermo appears to have done to the ray itself I get the feeling its gonna come back... but time will tell there.
Hoping you may have other ideas Duncan, but the thing that surprised me was how little flesh covers the ray, and the webbing between is almost fibrous also, meaning removal of everything appears impossible.
Anyway, pics of the attempt as follows;-
Pic of the dermo before attempt to remove;-
Having cut around the dermo and lifted off the tail, I attempted to scrape as much off the ray, initial attempt as thus;-
Close up showing how the rays themselves look damaged by the dermo
I then made further attempts to scrape away what I could from the ray, attempted to cauterise the bleeding, with a cotton bud, but without much success using some old LFH treatment I had.
I then carefully applied 6% (had no 3%) HP carefully with a cotton bud, trying to burn out anything left of the dermo, followed by painting on Mercurochrome 2%, AND Orahesive Powder and Lock & Seal Plus to seal it all in.
Orahesive powder
Then Lock & Seal
Koi back in the pond, total treatment time 22 minutes.
Hoping I was early enough, but looking at the damage to the rays, not confident at all.
Mark
if need be 
