I have an CPO (Dwarf Orange) crayfish. He's in a 16 gallon tank (24" long) with several bettas, several false julii corydoras, a couple of ghost shrimp, and a couple of nerite snails.
He doesn't bother the fish and will give up algae wafers to the corys if they keep going for it. He will only patrol the tank if he's alone, otherwise he'l stick to hiding spots and only patrol sometimes. My dwarf one is known to be very docile. I plan on getting a couple more, because he only gets to 1.6"
There is a common red species here in the US that gets up to 5 inches. Those aren't always too aggressive but can be. Do you know his color? That can be a good clue sometimes. There are red, orange, blues, etc.
I keep mine in a tropical heated fresh water tank. They can handle salt water for very short periods of time and can breathe out of water for days, though they are fully aquatic and can go right back in. My tank is 78F, but they can enjoy colder temps. They eat anything, but a select few will avoid eating plants, but will eat dead plants. Most other species will eat all you plants or at least move them around and uproot them all over the place. They love to climb!
It's a good idea to provide him with a diet that includes iodine and calcium. This can be found in food you normally feed to shrimp. Fluval has a product of pellets like that. It helps them in molting. From personal experience and from reading about others experiences they seem to molt more often then shrimp do. Mine has been molted twice a month, but the warm water may be increasing his metabolism causing him to do that.
I'll be honest. He will be most happy with a good amount of space and the bottom of the tank to himself. I've kept mine in a small tank (QT) and he rarely came out of hiding. I've also kept him in a 16 gallon tank by himself and he patrolled the tank non stop, as if he knew he was the only one there. With tank mates now he hides often but patrols on occasion. By patrolling I mean he travels around the outer edge of the tank (usually in search of food).