Well, while we are waiting on a few details lets see if we can collect a thoughts on how to bring out coloring in fish. Anyone please fell free to contribute ideas.
Feeding fish a varied diet that includes meaty, and flaked foods, vegetable matter, and seaweed will help to promote good health which will reflect in healthy coloration.
Also you can change your lighting around if it does not suit you. I have found that a 10K / Blue Actinic combination lighting does very well in illuminating the tank with nice crisp white lighting and brings out good blues and purples in fish.
Good water quality, which encompases the need for proper cycling, is also detrimental to healthy livestock and will sometimes impact the coloration.
Fish will naturally lose their coloring as they age so keep that in mind.
I'm sure I missed something here, if I remember I'll post it up.
P.S. - Welcome to FishTankForums!