My axie has little grey spots on his head

[Tee]

Hey guys, I am wondering if anything is wrong with my axie. He has grey spots on his head I never noticed before and he was extremely active all last night, swimming and walking around all night. When I turned my lamp on this morning he stopped swimming around. I am going to test my water today to see if maybe my levels are of and that is irritating him. Does anybody have any suggestions? Thank you!

 

[Tee]

Update: my friend who is experienced with axolotls believes it's just his pigment and that I have nothing to worry about. He also says the activity is normal. Checked my water levels and they are great so no worries!