Preheat oven to 450 F.
Arrange the carrots, onions and celery in a baking dish, cutting each into strips and mixing them together in a random order.
Coat vegetables in olive oil and season with salt, pepper, and oregano. Insert slices of lemon and parsley into the cavity of the fish.
Season with salt, pepper, rosemary, oregano, and herbs and add a touch of olive oil. Put the fish on top of the vegetables.
Bake without a cover for a duration of 30 minutes.
Squeeze fresh lemon on top and add some more parsley.Enjoy!