Stir together garlic powder, salt, pepper and paprika in a small bowl.
Cut cod into smaller pieces. Season all sides of the cod with seasoning.
Heat 2 Tbsp butter in a large skillet over medium-high heat. When butter melts, add cod to skillet. Cook for 2-3 minutes. Turn heat down to medium. Flip cod, top with remaining butter and cook another 3-4 minutes.
Remove cod from pan. Sprinkle cod with fresh lemon juice. Top with lemon slices and parsley.
Serve with simple salad of tomatoes and romaine lettuce. Serve immediately.