Thaw fish, if frozen. Rinse fish, pat dry. Cut into 4 serving size portions, if fresh. Stir together cornmeal and the 2 tablespoons bisquick. Sprinkle over both sides of fish. Lightly coat a 12 inch nonstick skillet with cooking spray. Add oil to skillet. Heat over medium-high heat for 2 to 3 minutes per side or until fish flakes easily when tested with a fork. Remove fish from skillet. Keep warm.
Melt butter in the same skillet. Stir in the 2 teaspoons bisquick, chili powder, salt, and cumin. Stir in half-and-half. Cook and stir until thickened and bubbly. Cook and stir for 1 minute more. To serve, spoon sauce over fish. If desired, sprinkle with parsley, garnish with lime slices.