Clean the mussels and clams and leave to soak in cold water until necessary. Clean the shrimp by removing the carapace and intestine, season with salt, pepper, oil and the zest of a grated lemon and store in the refrigerator until necessary. Fillet the scorpionfish and red mullet keeping the scraps aside; fillet then the mackerel.
Clean the squid and cut into thin slices. Clean the mantis shrimps removing the side legs and appendages along the back.
Prepare the broth fish by boiling in 3 liters of water, for about 1 hour and 30 minutes, the waste of scorpionfish, the waste of mullet, about twenty cherry tomatoes, a few peppercorn, 1 onion and 3 cloves.
Sauté in a pan with a drizzle of oil, a clove of garlic, a chili pepper, a chopped onion and a bay leaf, then dry everything with the addition of a glass of water. Pour the squid, sprinkle with half a glass of white wine and cook over medium-high heat for about 5 minutes, then add two ladles of broth and continue cooking.
After about 10 minutes, add the mackerel, the scorpion fish, the fillets of mullet, the remaining tomatoes and the tomato sauce. Add two more ladles of broth and continue cooking.
After another 15 minutes add the saucepans and continue cooking for another 5-6 minutes wetting with other broth if necessary. In the meantime heat some oil in a pan, sauté two cloves of garlic and 3 chillies and pour the mussels and clams stirring often.
Sprinkle with half a glass of white wine, let the alcohol evaporate, then close with a lid and cook until the shells have opened. In another pan blanch the shrimp for a few minutes.
Serve the fish soup by adding the mussels and clams and three shrimps each.