The scales are the armor plating on the fish to protect it from its
environment. Fish routinely will scrape themselves, removing some scales.
There is one carp, the silver carp, that has very fine small scales and
loses them so readily, that if you pick one up, you will be painted silver.
A google yielded the following page, which explains a little about scales.
http://www.newton.dep.anl.gov/askasc...9/bio99228.htm
Since they are the armor, and are routinely lost, I believe they will regrow
as shown in the page. I know that most of the koi that I have that I know
have lost scales, they have regrown. A bad ulcer, or other damage that
extends some distance, will, I believe, heal over without having the
cuticle, or whatever, and as such, the fish will have an area without
scales, scarring it forever.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

"Gary" wrote in message
...
I was given a large ( almost 24 inches) Koi. It had lost numerous scales on
either side. I believe the cause was trauma rather than a disease process
(there are 2 long lesions of 3 rows wide of scale loss) . I have had the
fish for over a month and it is doing just fine. My question is. Will these
missing scales grow back? Is there anything that I could do to help the
problem? Thanks