Cut fish fillets into portions, salt lightly and refrigerate covered. Peel garlic and crush with peppercorns in mortar, fold in 2 tablespoons olive oil.
Peel carrots and cut into slices. Wash celery and cut into centimeter-wide pieces. Roughly chop tender greens and keep for later. Roughly chop parsley as well. Peel and coarsely chop onions.
Drain and chop the peeled tomatoes, reserving the juice.
In a large saucepan, heat 4 tablespoons olive oil. Mix in minced onions and celery, sauté briefly. Then stir in the tomatoes.
Pour in white wine and bring to a boil. Add garlic mixture and season with salt.
Gradually add tomato juice and simmer on low heat for 5 minutes.
Add fish pieces to the saucepan. Cover and simmer for 10 minutes, after 5 minutes add the crab tails and finish simmering. Season with salt and pepper. Sprinkle parsley and celery greens over soup.