Hey check this out! the so called "half-moon" discus in a discus book I have...
I wish it said how this discus was made so it could maybe help you some more....
I was also thinking about the Black angelfish... how did they make that strain?
Because this "half moon" discus strain looks a lot like the half-black angelfish strain...
this one also looks a bit like those blue diamonds on that dallas site...