Naso changing colors.

I've had my Naso for a while and haven't observed him changing colors like a Foxface. Today I added some cleaner shrimps. Pretty amazing when my Naso lines up to be cleaned he changes colors. I thought that meant they were stressed but.. He doesn't seem stressed. One thing though, the cleaner isn't cleaning yet so maybe that's why the naso is changing colors.. maybe he's frustrated because he waits a long time and doesn't get cleanned. It's bizarre because he turns almost completely black then when swimming away from the shrimp turns back to normal colors. It's weird as even the Yellow on his forehead turns very dark.

 

I was JUST reading about certain fish that change colors to advertise to cleaner shrimp the other day. Naso tang wasn't mentioned however.

I think you should get a video, for scientific evidence and all ;D