For a truly good fish soup, you need various kinds of fish. In my case, I used the heads of a wels catfish, bighead carp and the meat of a zander.
Cut the fish into pieces, as well as the onions, celery stalk and carrot finely. Put everything in boiling water. Add the oil and salt to taste and leave the soup to come to a boil, until the meat of the fish begins to come off the bones.
Take the fish out with a slotted spoon and debone any meat that hasn't fallen off the bone.
Add the finely chopped potatoes, the finely crumbled fish and the rice. Once the potatoes soften and rice boils, add the ground tomato.
Shortly before removing the fish soup from the stove, add the chopped celery leaves, thyme and lovage. Before serving, sprinkle with black pepper and add some lemon juice for a sour tinge.
The fish soup ends up with a spectacular taste if you add the dregs from the kegs used in wine aging.