Sardine

A Sardine is a small, oily fish related to herrings. Portuguese sardines can be bought from the Apothecary in Diagon Alley. Presuambly, when conserved in olive oil, they can be used in potion-making.

Behind the scenes
Sardines play an important role in Portuguese culture. Having been a people who depended heavily on the sea for food and commerce, the Portuguese have a predilection for fish in their popular festivities. The most important is Saint Anthony's day, 13th June, when the biggest popular festival takes place in Lisbon, taking the people to the streets where grilled sardines are the snack of choice. Almost every place in Portugal has the summertime popular tradition of eating grilled sardines (or sardinhas assadas). This is probably why Portuguese Sardines were featured on the set of Harry Potter and the Chamber of Secrets (film).