Heat the oil in a large skillet with high sides over medium high heat. Add the garlic, fennel seeds, chiles, sliced fennel, 3/4 teaspoon salt and 1/4 teaspoon pepper, and cook, until fennel starts to soften and brown, about 4-5 minutes. Stir in the tomatoes, and cook until tomatoes break down, about 8 minutes. Stir in 1-1/2 cups water and cook until reduced and flavorful, another 3 to 5 minutes. Scatter the fish over the top and cook covered, 2 minutes. Scatter the shrimp over the fish, season with an additional 1/2 teaspoon salt and 1/4 teaspoon pepper, cover and turn the heat to low. Cook covered until fish and shrimp are cooked, about 3-6 minutes.

To serve, divide fish and shrimp between shallow bowls and ladle some of the broth and tomatoes over. Drizzle with more olive oil, top with the reserved fennel fronds and basil leaves and serve with the bread for dunking.