I have a question about Passover, where does the tradition of carp come from?

Mary is both right and wrong.

Gefilte fish is traditionally *best* made from a mixture of whitefish and pike, but it is also traditionally made from carp, especially by poorer Jews.

My great-grandmother not only made her gefilte fish from carp, she bought the carp an extra week ahead of the holiday, when it was cheaper, and kept it alive in the bathtub for not one week, but up to two. My mother could remember how she couldn't take a bath for nearly two weeks before Pesach, from the time her grandmother bought the carp until it was cooked.

The eating of gefilte fish is merely an Ashkenazic custom. It is said that you could tell the origin of a family by whether or not the women put sugar in their gefilte fish (sugar = Galitzianer, no sugar = Litvak). The dish originated in Renaissance Germanic foodways. So you won't find it mentioned in the Haggadah, which in its present form predates the Renaissance by several hundred years. Besides, the eating of carp, and/or gefilte fish, has no symbolic meaning.

Good, though!

It's a scaled fish - kosher.

It was an inexpensive fish to buy.

Most Jews were (and many still are) pretty poor.

Or are you talking about gefilte fish? Cause that's not usually made from carp, but from whitefish, also an inexpensive fish...it's basically Jewish meatloaf. You mix a few things into your ground meat, and you make it go longer and you can feed more people.

Actually, though, prepared gefilte fish is pretty expensive, today!