Damsel changing colors before my eyes!

[dixiechicken82]

We're starting a saltwater tank and have 4 bright blue damsels & 1 purplish damsel w/ a yellow tail. 2-3 of the blue ones are chasing & picking at a smaller blue one. 2 or 3 times tonight we have found that one being picked on at the top of the water in the corners of the tank (mostly hiding near the filter). While at the top of the tank it turns almost black. We had to coax it out of the top of the corners into deeper water and seconds after going to the bottom its bright blue color comes back! Is this a warning sign? Is it sick? We took it out and put it in a fish bowl for tonight, and after a minute of being in the fish bowl it turned nearly black again. Is something worng?? What do we do?? Please help!

 

[shadow]

Damsels will loose color when the hide ie lights go out and when they are turned on they will gradually gain color.