Spice fish inside and outside with salt and pepper. Fill fish with crushed garlic, thyme and rosmary.
Cover kitchen foil with olive oil and wrap up every fish separate. Grill slowly.
Peel potatoes, cut into cubes und boil them in salted water until tender. Remove stalks of the mushrooms. Thread the chunks of potatoes and mushrooms on skewers, alternating olives and grill them too. Sprinkle with lemon juice and olive oil from time to time.