Preheat oven to 400 degrees F. Coat a rimmed baking sheet with cooking spray.
Place ranch dressing in a shallow dish. Place potato chips in another shallow dish. Dip catfish fillets into dressing, then into potato chips, coating completely on both sides; place on baking sheet.
Bake 18 to 20 minutes or until fish is firm in center and the coating is crispy and golden.
Meanwhile, in a medium bowl, combine corn, bell pepper, scallions, lime juice, salt, black pepper, and tequila, if desired; mix well. Serve corn relish over catfish.
