Scrape the mussels then wash them in abundant cold water and drain. Place a peeled clove of garlic and the chilly pepper in a frying pan, sprinkle with the wine and a spoon full of oil. Put the pan over a high heat for a few minutes, tossing it from time to time until the mussels have opened.Remove from heat, eliminating any closed mussels, drain and filter the cooking water through a clean tea towel and set aside. Shell the mussels (keep a few shells for garnishing). Remove skin and insides from the squid, wash thoroughly, dry and cut the sac into rings and the tentacles in halves. Shell the prawns, remove the black thread and wash. Drain the tuna from its oil and mince it coarsely.Blanch the tomatoes in boiling water drain, peel, deseed and drain them from their juice and then mince. Wash the parsley and mince it with the peeled clove of garlic. Warm the remaining oil in a pan with the chopped parsley and the garlic, add the squid and brown slightly, constantly tossing with a wooden spoon; add the tomatoes, season with a pinch of salt and ground pepper and keep cooking for about 10 minutes, adding a bit of the mussel’s cooking water.Add the prawns and the tuna and cook for 3 minutes, at last add the mussels, including those with the shell, and keep cooking for another 2 minutes. In the meanwhile cook the pasta in a large saucepan with plenty of boiling salted water, drain it al dente add it to the fish ragù, sprinkle a pinch of oregano and serve immediately nice and warm.