| If they are both true percs, I think the issue you would run into is having one female and the rest male, regardless of coloration. If they are different species, you could pull it off in a larger tank, but I wouldn't dream of it in a 15 gallon. And the typical yellow-tailed blue damsel is very territorial and may cause big problems. I had one that bullied fish 3 times it's size. It was great until it got to about 2 inches, then became intolerant of ANYTHING. And this was in a 65. I'm not suggesting you don't get one, but be ready to move it or get rid of it if problems arise. | 
