Sprinkle the cavity of the fish with salt and 1 teaspoon of the fennel seeds.

Place the fish in a colander set over a bowl and refrigerate for at least 1 hour and up to 3 hours to season it.

Preheat the broiler to maximum.

Insert 1-2 garlic quarters in the cavity of each fish and brush on both sides with oil. Sprinkle with salt, arrange the fennel at the bottom of the pan and place the fish over it. Βroil for 15-20 minutes, and carefully turn the fish. Arrange a few lemon slices over each fish and continue to broil, until cooked throughly, another 15-20 minutes, depending on the size of the fish.

Meanwhile, combine the lemon juice and the remaining 1 teaspoon fennel seeds in a shallow bowl. As you take the fish out of the oven, open them discard the backbone and sprinkle with some of the lemon mixture. Whisk a few tablespoons of oil into the remaining lemon mixture (use about twice as much oil as lemon mixture), drizzle over the fish and serve.