Cut catfish fillets in half; set aside.
In a pie dish or plate, combine corn muffin mix and Cajun seasoning; set aside. In a pie dish lightly beat egg with 1 tablespoon water to make egg wash; set aside.
Dredge each catfish fillet in the flour; dip into egg wash and coat with corn muffin mixture. Set aside on a plate.
In a deep-fryer or large pot heat oil over medium to medium-high heat to 375 degrees F. Fry catfish until golden brown, about 6 minutes. Remove to plate lined with paper towels.
In a small bowl, stir together all ingredients. Set aside.
Spread warm garlic bread with remoulade sauce. Build sandwiches with fried catfish and remaining ingredients.