I tried that about 10 years ago. Bought some from a grocery store and headed to one of my small ponds. Fatheads were doing OK in it. I put them on the bank and they didn't do much. So I put them in the water and some promptly crawled out back onto the bank. I left and came back later. More were on the bank and I put them back in the water. The next morning I went to look. Evidently all had crawled out of the water and committed suicide by coon.

I called a Louisiana crawfish producer and asked questions. He said that while they were still alive and suitable for eating, they were mostly dying from being shipped and displayed on ice.

I haven't tried it since.