Crayfish are different colors around the country depending of species. I use to have a link to the different habit ranges until my computer crashed (hopefully someone will come along and post it). Here in Maryland we have the Virile and Rusty craws which I have caught in the local waters. Both of these are brown but one has green craws, head and tail. I use this to my advantage by making a brown jig with a GP head and GP trailer. I learned the secret to why PB&J works so well in MO when I spent 17 weeks there for an Army school. All the craws I found in MO were brown with a purple hue to them.
Allen