Patch

[Rabid Glass Shrimp]

My Platy male has a white patch on his head.
It is not fuzzy like fungus an is not ich. What is it?

[Little Embers]

Can you get a picture? It would help. Could be natural colouring, missing scales, could be many things. Is it spreading, how big is the patch and how long has it been there? What is your water parameters, tank size and other tankmates?