Clean the bass, removing the insides and slice into fillets and then into chunks. Clean and rinse the fennel and slice into thin slice. Put 3 tbsp of oil in a pan, add the fennel slices and brown briefly stirring with a wooden spoon.Season with salt and pepper, add a bit of water, cover with a lid and simmer for 12-15 minutes. In the meantime place the leftover oil in a pan, heat it, place the bass fish and brown.After a couple of minutes, pour the white wine and let it evaporate, then add the fennel. Cook the pasta, drain all dente, dress it with the fennel and bass ragù at last, garnish it with fresh fennel leaves.