Crabs are probably a good feed for chickens. One caution though, I have read that when adding crab meal to chicken feed, you should not add more than 2.5lbs./100lbs of feed. I think it is because the shells are high in selenium. This comes from the website of Harvey Ussery, who seems to know what he is doing. That being said, the guy that makes the feed I use has 5% in his layer feed and it is a Fertrell recipe. I would imagine that the wet pieces of crabs would be less concentrated than they dried meal, but you may want to go easy on the amount or research further for yourself.