I was feeling daring today. If you’re ever tried to photograph a black Moscow guppy, you’ll know these are probably the most difficult fish. Black is essentially the absorption of color or lack of light. And you need light obviously to see something or take a photo. A good photo of a black fish will pull out other subtle colors, like purples, blues and greens.
Terry Aley's Guppy Site 
Terry, Your photos do well in exemplifying common origin of all Moscows; Blue, Green, Purple, Red and Black. Regardless, of color pigment or melanophore additions to individual phenotypes, underneath each is still a “Blue Moscow” comprised of blue iridophores…
Now that you mention it, I can totally see a buried blue Moscow in these.
These photos with the blue showing through change my mind about black guppies. Beautiful.
I have a photo of your posting that I like, so can I use it non-commercially?