Pre-heat oven to 220°C / 428°F. Cut lemon zest into strips. Squeeze lemon. Blanch zest, carrots and fennel in salted water until al dente, refresh under cold water. Chop the herb fennel with the celery leaves and mix with vegetables. Rub each fish inside and out with “Scent of the Macchia”. Stuff fish with vegetable mixture. Arrange each fish on a separate sheet of paper, drizzle with lemon juice, place sliced butter on top. Lightly brush the inside edges of each parchment packet with egg white. Place remaining sheet on top of each fish. Working around the edge, make small, sharp folds holding both layers together securely to seal in the fish. Bake for 30 minutes.