Divide fish fillets into portions, sprinkle with olive oil and with half of basil.
Place on a plate, cover with plastic wrap and marinade in the refrigerator for 15 minutes.
Wash and halve the zucchini and cut into thin strips. Peel tomatoes, remove stalk and seeds and chop into small pieces.
Season fish with salt and pepper. Heat heat oil and 1 tbsp. butter in a pan. Fry fillets on both sides and then keep warm. Pour sieved tomatoes  in the pan.
Fold in rest of basil, zucchini and tomato cube. Season with salt, pepper and crushed garlic and boil down.
Serve fish upon the sauce.