White marks on yellow watchman goby

[Bonz]

My ywg has two white marks on his right side for a few weeks. I thought he might of scraped himself but there is no healing. He does not show any sign of stress. But i dont know if its something to worry about. My parameters are all normal and wc are 25% every two weeks. The one spot is just below the front of his dorsal fin and the other is at the middle of the back side.

[cls8s]

My bicolor blenny gets white spotted over his entire body when stressed the least little bit. Water change, moving live rock. Etc