In a medium bowl, mix all ingredients until well blended.
Combine cornmeal, flour, salt, cayenne pepper and garlic powder.
Coat catfish with cornmeal mixture, shaking off excess. Fill a large, heavy skillet half full with vegetable oil. Heat to 350° F.
Add catfish in single layer and fry until golden brown, about 5 to 6 minutes, depending on size.
Remove and drain on paper towels.
Spread butter on each side of rolls, and lightly brown in a large skillet.
Smear toasted bread with Lemon Aïoli. Layer tomatoes, spinach, bacon and catfish on bread.