Tang Discoloration, Black dots, and Lateral lines

[ReefApprentice]

My kole tang loses color but when it gets scared gains it back really quickly. Is this because it does not feel unsafe so there is no need to be dominantly colored? Also my yellow and kole tangs have lateral lines looking kind of like veins from head to fin or so. Also, the yellow has a lot of black dots on it.

Any help?

Thanks

[FishTechNH]

Black dots are parasites. Sounds like HLLE going on as well probably stressed from the two tangs living together.