Comment on Longhorn Cowfish by DavidGrieninger
Sorry I'm afraid I don't know 
I guess their using it as a kind of warning for other fish not to eat them.
I guess their using it as a kind of warning for other fish not to eat them.
It's okay. I was just curious because I recently watched a documentary about fish colors.
Sounds interesting 
It was. I did not realize there were so many sea creatures that could change color depending on the time of day or their environment. You only hear about chameleons doing that.