Preheat broiler to high with oven rack 6 to 8 inches from heat. Combine 1 1/2 teaspoons oil, 1/2 teaspoon each of salt and pepper, and paprika. Place fish on a baking sheet; rub with paprika mixture. Broil fish until beginning to brown and fish flakes easily with a fork, 10 to 12 minutes. Keep warm. Peel grapefruit and orange. Using a small knife, cut fruit into segments, and coarsely chop. Whisk together cilantro, lime juice, garlic, 2 tablespoons oil, and 1/4 teaspoon each of salt and pepper; stir in onion and citrus segments. Spoon salsa over fish.