Fungus? Bacteria? Sick Koi?

[KatieG]

My baby koi is as chipper and cheery as normal, but it has these patches of white on the top of its head and along the back to the dorsal fin. The center of the head patch looks a little green. I can't tell if this is a fungal or bacterial infection. I tried to take pictures, but it won't hold still. Hope these help. None of the other fish are ill--that I can tell.

Pictures to follow.

Edit: There are no white spots on any fins on any fish in the tank. These patches on the koi are not really raised. More smooth.

 

[KatieG]

 

[jlk]

Hi! We need some more info in order to be able to help. Where is the koi? If he is in a tank, what size? Stocking? Water parameters? Water change schedule (%/#wk)? Thanks!