Yes, they are indeed the easiest to breed, and you're able to eat them. I have 5 myself, and 3 of them just gave birth to about 50-60 new Crays. You only need one to start reproducing, how big is your tank?
55 - Jack Dempsey/Rainbow Shark/Cobalt blue cray
46 - Marmorkreb tank
20 - Guppy farm
10 - Betta Tank
5 - Marmorkreb fry