Fill a four gallon stockpot ⅔ full with water and bring to a boil over high heat. In a small bowl, combine all of the Fish Boil seasoning ingredients and set aside.

To the stockpot, add potatoes, lemon halves, onions, bay leaves, salt and half of the seasoning mix. Cover and bring to a boil. Reduce heat to medium-low and cook for 8 minutes. Add corn, celery and sausage and bring to a boil; cook for an additional 5 minutes.

Add crawfish and return to a boil; cook for 8 minutes more. Remove from heat and drain off liquid. Add the other half of seasoning mix and melted butter and give it a little mix. Cover the stockpot and let everything steam together for 10 additional minutes. Pour contents of stockpot out onto a table covered in newspaper or parchment paper. Remove bay leaves and serve.