Why does my keyholes have pale colours?

[FeliciaC]

Hi! About a month ago I bought seven keyhole cichlids to my 100 gallon. I bought them from a person and he delivered them to my house. At first I thought they looked a bit pale but they where stressed so i considered it to be normal. But their colours havent changed! As you can see in the picture (here it is: http://postimg.org/image/algu6o7ex/ ), the black markings are really pale, and on some keyholes it barely exists. I dont understand why. I have a lot of hiding spots and their only company is glow light tetras and an ancistrus. I give them cichlid pellets, flakes, frozen foods and i change 15% of the water every week. I use easylife ffm. The keyholes are eating well and doesnt seem to be sick. I need help

 

[Wmc2009]

I have two full grown adults that I've had since juvie size. Their colors have always fluctuated like that too. I think they're just extremely skittish and everything freaks them out. When they do actually chill out and show they're colors it's impressive though. Someone else with more experience might have a better answer for ya though.