disease/parasite or somthing else? yellow goby

[Aquaria]

think the guy at the LFS grabbed a diff goby then the one i wanted when i wasnt looking because he didnt have these markings in there tank. today i got home and noticed that my goby paired with my pistol less then 12 hours after addition of him YAAY then i noticed gray markings they look kinda patchy almost like the scales/skin is still there but color is gone? im not sure what else i can say to help...hes eating well and otherwise looks healthy heres pics