In a large saucepan of boiling salted water, cook the pasta until al dente. Drain and coat lightly with oil. Set aside.
With the rack in the middle position, preheat the oven to 180°C (375°F).
In a bowl, combine the cottage cheese, pesto and chicken broth. Season with salt and pepper.
Spread one quarter of the cottage cheese and pesto mixture on the bottom of a 23 x 33-cm (9 x 13-inch) baking dish. Cover with a layer of noodles. Add another quarter of the pesto mixture. Sprinkle with 125 ml (1/2 cup) mozzarella. Cover with another layer of
noodles. Lay the fish fillets on top. Season with salt and pepper. Add another quarter of the pesto mixture. Finish with a layer of noodles and the remaining pesto mixture and mozzarella. Bake uncovered for about 45 minutes. Brown under the broiler to finish. Let stand for 5 minutes before serving.