I believe that the color fading is diet related. I struggled to get them to eat a variety of foods. I also tried soaking foods in vita-chem, garlic. Zoe, vitamin c and selcon but the color still faded.
I read that they were plankton eaters so I tried both frozen and dry plankton. I could get them to eat the dry plankton soaked in selcon but it did not help the color either.
Both pairs would eat PE Mysis, scallop, shrimp and silverside. They would eat pellets only on occasion and not with any gusto. No interest in flake.
The color fades over the course of about 6 months.