Heat nonstick skillet over medium-high heat. Add 1 tablespoon of olive oil.
Drizzle fish with remaining olive oil; then dust with seasoning on each side. Cook seasoned fillets 4 to 5 minutes per side, or until brown, turning only once. Transfer to a plate, and allow to cool slightly before cutting in half.
Place cheeses, pimientos, mayonnaise, mustard and spices in a large bowl, and mix thoroughly.
Heat a large cast-iron skillet over medium heat. Spread pimiento cheese on 8 pieces of bread. Add catfish and tomato to 4 of the bread slices, and top with remaining bread slices.
Brush with melted butter, and cook 3 minutes on each side, or until browned and sandwich is warmed through.