Blue Crayfish (and practically all crayfish in general) are best suited to a species only tank, and even then depending on the size of the tank only keeping one or two in the tank. They can be pretty aggressive to each other and can and often will eat fish kept with them if they can grab the fish while it is sleeping or resting. Crayfish will also devour any live plants you try to keep with them, they are usually opportunistic feeders but do like their vege's best.
They also require a well aerated and filtered tank, as they can be rather messy.
Also have a firm fitting lid for the tank, crayfish are excellent escape artists and large ones have been known to even lift glass lids off their tank in escape bids.