Dojo Loach Has Brown Head

[Phisher84]

I bought 2 Dojo Loaches (chinese weather loaches) about 6 weeks ago, and one of them has a brown spot on the top of his head and it hasn't changed. Should I be concerned about this? They're both active and playful and seem really happy and healthy.

 

[Gourami123]

No its just a natural spot. some dojos have quite a few of them