I have read alot that light dempseys generally mean sick dempseys. Mine changes color in the blink of an eye. If its hanging in its flower pot its a dark brown/green, with spectacular coloration in her fins, etc. But when she comes out and swims around, she turns a light brownish/tan color. Nothing seems to be wrong with the fish, it eats, fins are always spread out, seems to be growing at normal dempsey rate etc. I think it might be because I have white gravel, there also isnt a back ground and the tank is against a white wall. The fish is about 6.5 inches, got her last summer when she was a baby. What are your thoughts on this.