From time to time, Frank Tropiano will drive past the tiny structure he called home after he and his parents, three sisters and his grandparents arrived in this country in 1966, a structure that was attached to the rear of the house on Susquehanna Street in Homewood, Pennsylvania.

The humble apartment was nonetheless a big improvement over the even tinier structure with no plumbing or electricity they left by boat from Siderno in Calabria, Italy.

Although only 10 years old at the time, Mr. Tropiano, now 68, said he remembers it as if it were yesterday, feeling both happy and relieved when, a few days before the family’s first Christmas Eve in America, his mother and grandmother came home from the Strip with baccala and started soaking the pungent-smelling cod.

He said he felt a solace that immigrant children often crave in new surroundings when he saw his family starting the preparations for the Feast of the Seven Fishes. For him, it was always the highlight of the Christmas season.

“When you are a kid, you don’t want things to change. We had come to a new country, and everything was so different here. I can remember the wave of comfort surrounding me, knowing Christmas Eve in America was going to be no different than Christmas Eve in Siderno, in that we would have the seven fish we’d always have the night before Christmas.”

For the next week, Americans of southern Italian descent will flock to fish and epicurean markets across the country to purchase a wide variety of seafood to prepare for the longstanding southern Italian tradition of fasting on Christmas Eve. The fast concludes with a bounty of seafood dishes, many of them fried in olive oil and almost all of them accompanied by some sort of pasta.

Mr. Tropiano said that in Siderno, most of the family — cousins, aunts, grandparents — all lived next to each other and would spend the entire day frying and cooking. For him the whole day took on an aura of anticipation and festivity.

The tradition has its roots in the Catholic faith tradition of a fast from meat before a holy day, so people eat fish instead. The reason for the number seven is less clear. Mr. Tropiano said he believed the number referred to the seven sacraments. “Our meal actually also has to consist (of), in total, 13 dishes, each one for one of the apostles and Jesus,” he said.

Coming here is a ritual for thousands of Italians, like the Tropianos and my own family — a rite of passage that has been handed down from each generation, often from mother to daughter, to continue the family feast that not only celebrates their faith but also brings people together over the other great connector: food.

When my own grandparents immigrated here from Strongoli, they settled on Yuba Alley in the Hill District. My grandfather Antonio would go to the Strip with my Uncle Bill and pick up the smelts, sardines, baccala and other fresh seafood for my grandmother to prepare. I carried on that tradition in our family, first taking my children Shannon and Glenn in the ’80s when they were toddlers.

It is a custom I have continued with my grandchildren Eleanora, Milo, Louisa and Rocco, who of course all scrunched their noses last week when seeing piles of squid on ice at Wholey’s. But they will still dutifully stuff them with me next weekend as they become the bearers of the ritual going forward.

My father, Ron Zito, 87, recalls the dishes his mother served, especially the snails.

Mr. Tropiano emphasizes the traditional fish dinner in Siderno was simple in comparison to what he and his wife, Dee, will be serving to his adult children and his grandchildren next Sunday at their home in Penn Township, Pennsylvania.

In Siderno, “we had fried calamari, sardines and we had anchovies and then the baccala,” he said. “We didn’t have access to a lot — remember, my father would go to the market on the donkey, and whatever fish they had there fresh, he got. Sometimes it was seven, sometimes we didn’t have enough money for seven, you understand.

“We didn’t have much, but we had a lot.”