Has anyone else seen this happen?

[X the Outsider]

Over the weekend I was at a LFS looking around. I started watching a dogface puffer swim around. The dogface changed colors for no reason I could see. He was swimming, and then sat by a rock for awhile. Then his color went from a light brown to a dark brown. I've never seen this, and was wondering if anyone else had ever seen it?

[electrikat]

Maybe stress or fright? Maybe the lights had come on recently because some fish get washed out without the lights on and color up a little while after the lights come on.

[scuba_steve]

you made him blush

[tripper]

I had a dog faced puffer and he would change color occasionally. He was almost always that light brown color, but when he was stressed or scared, he would get very dark. If I ever had my hand in the tank he would get scared and change color. As soon as I took my hand out, he would be light again and would be right at the front of the tank looking for attention. He was a riot.