Just a note on Astaxanthin… It is a carotenoid. It can/does alter shrimp coloration. But not super-fast. It happens much less than abruptly.
I.E., you can feed Yellow Neos a ton of Astaxanthin and they'll eventually turn green/blue green. (Happens with spirulina overfeeding, as well) Takes more than a week, though. And it takes much more time than a week for the carotenoids to dissipate than a week.