Note: Crawfish do have a dark vein that you can remove before eating. *It will not hurt you to eat it*. In young crawfish, that vein will turn semi clear once the crawfish is purged. But as they get older, the vein stays a dark color, so it makes it look like it is dirty, which usually is not the case. This is why it’s just easier to remove it. If you push in the tail when you are twisting, the vein will separate from the meat.