BOILING SEAFOOD For a dozen crabs or 5 pounds of shrimp or crawfish. Steps: In a large pot add enough water to cover seafood completely, 1 Tbsp. Zatarain's Liquid Crab Boil and 5 Tbsp. of salt. Bring to a rolling boil. Add seafood and boil crabs vigorously for 20 minutes, crawfish 15 minutes, and shrimp 2 minutes. Allow seafood to remain in water 5 minutes after boiling. Adding 2 tablespoons of vinegar to the water makes crabs easier to pick.