The seven fishes eaten on Christmas Eve are anchovies, eel, flounder, herring, mackerel, mullet, and sardines. They are typically served as appetizers or side dishes to the main meal, which is usually a roast or stew. The tradition of eating the seven fishes is believed to have originated in Southern Italy and is now celebrated in many other parts of the world. It's said that the tradition was started as a way to celebrate the seven sacraments of the Catholic Church, and the fish were seen as a symbol of Christ's sacrifice.