Thaw fish, if frozen. Preheat broiler. Rinse fish; pat dry with paper towels. Set aside. In a small bowl combine salsa and garlic; set aside.
In a medium saucepan bring broth to boiling. Stir in couscous; cover and remove from heat. Let stand about 5 minutes or until liquid is absorbed. Fluff couscous with a fork. Stir in green onion.
Meanwhile, measure thickness of fish. Place fish on the greased unheated rack of a broiler pan. Sprinkle fish lightly with salt and pepper.
Broil about 4 inches from the heat just until fish flakes easily when tested with a fork. Allow 4 to 6 minutes per 1/2-inch thickness of fish. (If fillets are 1 inch thick or more, turn once halfway through broiling.) Spoon salsa mixture over fish; broil about 1 minute more or until salsa is heated through. Arrange fish on couscous mixture. Serve with lime wedges.