A type of freshwater crustacean that looks like a small lobster. Typically, a crayfish will be 3 to 4 inches in length, but at times they may reach sizes as large as 8 inches in length. Also known as crawfish, crawdad, and crawdaddy, this shellfish is a common ingredient that is often used in Louisiana Creole recipes. Crayfish may be prepared by steaming, boiling, broiling, or grilling.