3 tablespoons reduced-fat plain yogurt
2 tablespoons finely chopped onion
1 tablespoon fat-free mayonnaise
1 tablespoon Dijon mustard
1 tablespoon ketchup
1/2 teaspoon dried thyme
1/4 teaspoon grated lemon peel
1 teaspoon paprika
1/2 teaspoon onion powder
1/4 teaspoon salt
1/8 teaspoon cayenne pepper
4 (4 ounce) fillets catfish
4 lemon wedges