Simply Koi and More Koi

Hi again....
Here's the health query.
This fish is another that has come into my possession, but it has a fairly severe swelling on the right hand side gill plate. There is no pitting or sign of damage to the gill plate nor any softening. You can see a white mark on the first picture, and it honestly looks as if this would burst with a good squeeze if you found it on your face in the morning!! The fish is in good health and doesn't seem to have any issues, but I wonder what might have caused the deformality and whether or not I should expect it to clear up or whether I should be looking to treat it?
Many Thanks (Again!)
Louie

P.s. Oh yes...... Wht the hell is it, anyway!

May be a Hanna Shusui or a Doits hariwaki ?? any chance of a better photo side on of the gill plate could it be Hikui ??

from the photo it looks more like a deformity than a health issue, better picture would really help.

I think you're probably right about the deformity. Should have got some better pictures, but to be honest there really isn't much to see! Guess I've just got a wonky koi!