Changing colors

[miles o'reef]

This past Friday, I brought home a yellow watchman goby and pistol shrimp. They have been doing fine thus far in my QT but I noticed something interesting yesterday.
When I turn on the lights in the morning, the goby had lost almost all of its vibrant yellow color. I thought that it was sick and about to die. But, when I checked on it a few minutes later, all of its color returned.
As anyone else observed this with their yellow watchman gobies or other fish?

 

[sebae0]

i have seen fish do this at night also, it is a type of camofluage to help against predators while sleeping. there has been plenty of post of yellow tangs doing this on this site.

 

[leviwin]

I have a tang and a goby that do that. It also happens when they get scared.

 

[ophiura]

It is actually called "pajama coloration" and it is noted in many, many species of fish. Basically, it is their sleeping coloration. It may simply mean that the fish is paler...but in some cases the fish may be darker, duller, or develop patterns not typical of their day coloration.

 

[miles o'reef]

Interesting, thanks for the replies.