Rinse fish and pat dry. Rub shallot and half of the dill onto the surface of the fish and sprinkle with salt and pepper. Saute in butter over medicum heat for about 5-8 minutes per side or until cooked to an internal temperature of 150 degrees. Add 1 1/2 Tbsp lemon juice and 1/4 cup Alfredo sauce to the skillet and cook fish, skin side up, for 3-4 minutes or until sauce is hot and bubbly. Meanwhile, cook pasta according to package directions. Drain well and toss with remaining Alfredo sauce, dill and lemon juice. Place on a platter and top with fish.