Cut each fillet lengthwise into 3 strips, each about 1 1/2 inches wide. Thread each strip onto a skewer. Lay them in a shallow bowl. Combine 1 teaspoon of the Creole seasoning, the salt, cayenne, mustard, and buttermilk in a small mixing bowl and stir to blend. Pour the mixture over the catfish, cover, and refrigerate for 8 hours. Remove the fish from the refrigerator. Heat the oil to 360 degrees F in a large deep cast-iron skillet. In a large mixing bowl, combine the flour and the remaining 2 teaspoons Creole seasoning. Dredge 2 to 3 skewers at a time in the flour, shaking off any excess. Fry them in batches until golden brown, about 4 minutes on each side. Drain on paper towels. Serve hot with the remoulade sauce.
Put the green onions, garlic, horseradish, mustards, ketchup, hot sauce, Worcestershire, lemon juice, egg, salt, and cayenne in a food processor or blender and process until smooth about 30 seconds. With the motor running, slowly pour in the vegetable oil through the feed tube. The mixture will thicken. Transfer to a container, cover, and refrigerate for 1 hour before using. Best if used within 24 hours.
Combine all ingredients thoroughly.