Solar Fairies
Scott's Fairies
Temmnick's Fairies
Blue Scaled Fairies
Black-finned fairies
Exquisite Fairies
All these fish tend to lose their colors a bit if they don'y have a harem of females. When I say they lose colors its primarily their beautiful nuptial or courtship colors. Obviously without a mate to court the darker colored fairies (blue's/browns/greens) tend to
fade.
The in-between group - this means they may fade a bit but not alot:
Rhomboid Fairy
Pyle's Fairy
Pink-Margin Fairy
Goldbar fairy
Yellow-flanked fairy
Here are the fish that tend to keep their colors well, regardless of wether or not there is a harem:
Labout's
Flame
Social Fairy
Conde's Fairy
Lineatus Fairy
Yellowfin Fairy
Lubbock's Fairy
Rosy-fin Fairy
Orange Back fairy
(It seems to me that the fish that have the red-orange coloration or the hot pinks & yellows tend to keep their colors better than the blues & greens)
Please note that the fish listed in this post are the only fish I have had experience with or owned.......if a fish is not listed here, wether it be as a color fader or not, then I cannot confirm if they are faders or not.