BlueCrayfish.com

Yes color is totally depends on diet and it is observe that generally some different food contains change color of crayfish and Crawfish Tails color is changes to original also dark blue too.I also have 2 male and 1 female crayfish and right now one male change to complete dark blue and female also on the way don't know what's the reason but Crawfish Tails color still showing 2 different color surprise for me is any one have soloution for this please reply soon.
http://www.lacrawfish.com/Crawfish-Tails-C32.aspx

The crayfish's color is often very related to their diet. What are you feeding them? I've read various things on encouraging color brightening/darkening in crayfish, most of it anecdotal so I'm not sure how trustworthy it is.

Hello, Good Evening.

When I bought my Crawfish they were little blue, were gradually becoming more colored. For a while now they are darkening, turning brown.
I have one female and four males. They are well, healthy and crossing and having puppies, but they are very dark.
Is there adequate food to improve the color?