So you caught and kept wild crayfish?? Cool!! If they're fine about being in an aquarium, I think it wouldn't hurt to keep them. I know this one place where I live where there's a machine (like one of those crane games, where you catch the stuffed animal) that has live lobsters in it. You pay $1 to try to get one, and if you do, you go and tell the manager that you got one. It's extremely hard cuz they move around a lot, but if you do get one, then you can do whatever you want with it. Cook it and eat it, or, my version, keep it as a pet. I think you would need a 20 gallon tank for one of those things. They're pretty big!!*crazysmil