1. Preheat oven to 425 degrees.
2. Rinse fish and pat dry.
3. Make three diagonal cuts in the flesh of the fish on both sides.
4. Set on two parchment-lined rimmed baking sheets.
5. Divide garlic, fennel fronds, lemon slices, and rosemary sprigs among the fish.
6. Place bay leaves in the cuts on top sides of the fish.
7. Roast until the flesh is opaque, about 20 minutes.