That's stunning pic! I wonder what lighting is on the tank, that can make a huge difference. There's lfs that uses different lights than I do & their fish look great! They don't grow much if any plants with them but that's important to me.
I would also guess the male in the pic is in top breeding form & a younger but fully adult fish with an excellent breeding line & excellent foods. With rainbows there are often different locations that the fish are collected in the wild, different rivers can have at least slightly different coloring. I don't know that is true with Bosemanii but it is with some 'bows.
Been browsing YouTube. Gary Lange has a strand he's been raising and Seagrest supposedly has those lines now. Definitely more colorful. Perhaps they could turn out something like this. Not sure. Lake Aytinjo I think?
You already know more about them than I do, lol. I've heard of Gary Lange & his high quality 'bows but I don't recall what species or strains were mentioned.
Good luck & I hope you have deep pockets for both the fish & shipping , it can be very expensive to get your heart set on a very specific kind of fish. But if you do, go for them! You're not a newbie, you should know the basics & lots more
I have a tendency to nerd out on this stuff when something catches my interest. Watched a youtube video where Gary says Seagrest has his line now and it should be better than what has typically been available. Checked their online catalog and it shows this is what they have (doesn't specify GL, but they are Lake Aytinjo). Just have to find a LFS who will bring them in, hopefully without astronomical costs. I can't pay big bucks, may have to stick with what I can get.
Mostly I was just curious if any average hobbyists are actually getting that kind of color at home.