First of all, I know this is an old post.
I want to share my blue crayfish story. Ive had him in this 48 gallon vertical tank for almost 2 years. Hes pretty cool, although he hides during the day mostly. I added him to a nicely planted tank, and he chopped up every plant he could get his pincher on (when I got him, he only had a left pincher. the right was totally missing. it has sense mostly grown back). He has only killed a couple of small guppies and one goldfish. but i always get tons of compliments, and when he comes out to eat and explore, he is the life of the tank.
that being said, I wont get another one once he is gone. lol
here he is attacking (unsuccessfully) one of my snails
here are the plants before he chopped them all up:
here is is, first time in the tank (note he only has one claw)