Good to know. It seems like it may be dependent on 'mood' as well. When I went to put the glass bowl in, I had to shoo him to his 'stick'. His color changed immediately from bright green to dark gray / green. The tank door was open just a couple of seconds....maybe long enough to change the climate and precipitate the color change, but maybe not. I'm a numbers guy....I'll stick to the numbers. Thanks again, everyone. I'm sure I'll have more questions.

Kevin