The European sardina pilchardus. Often called a pesce azzurro; a small one is a sardina (in general, but see below!). Not to be confused with a sardoncino or sardela which is really an anchovy (alici or acciuga).
Italians like them fresh more than canned, as in the classic Sicilian dishes pasta alla sarda and sarde a beccaficu, grilled and stuffed with raisins, pine nuts, lemon peel, parsley and breadcrumbs. (The beccafico is a warbler that 'beaks figs' and was—and sometimes, still is— hunted for its sweet taste and roasted whole; the rolled sardines are facetiously said to resemble them).
Another Sicilian classic is sarde allinguate ('tongued sardines'): the sardines are butterflied to resemble tongues, marinated in salt and vinegar for two hours, then buried in flour for at another hour (so the flour sticks) before being deep fried.
Image by juantiagues