Pet or Food? - Blue crayfish - not your typical lobster

The bright colors you see on those crayfish is the result of selective breed in captivity. All crayfish were brownish in color in their original wild forms. If you attempt to cross different colors of crayfish, their offspring will just revert to their wild brownish form.

The same goes for some aquarium dwarf shrimps. Such as red cherry shrimps, yellow shrimps, etc. They are basically the same species with different colors resulted from captivity selective breeding. Any "cross" will revert them back to their wild forms which won't be pretty any more lol.

Of course there are certain wild crayfish/lobster/shrimp out there with natural colorful forms, but they are rare since bright colors often make them easier prey because it would be terrible as camouflage lol.