So I thought all of my crabs were PPs, but Gregor is like, ridiculously maroon. He doesn’t have any of the usual coloring. (That’s him in the white shell, I’ll try to get a better photo later) So… What’s up with that?
He’s probably just bigger, and thus darker. Thats how Johnny is.
Crab coloring is strongly related to diet. A diet high in carotenoids will amp up a crab’s coloring like you describe. You can find astaxanthin powder in the tropical fish section of most pet stores or do a quick search on foods high in zeaxanthin, which is the easiest type of carotenoid for crabs to convert to the astaxanthin their bodies use. Astaxanthin is why my Benny is almost completely purple.