Belly of Bonito in Olive Oil. The belly or belly of bonito is the juiciest and softest part, being elaborated fresh and artisanally during the campaign or Costera of Bonito del Cantábrico during the summer months, a true delicacy in canned form. Conservas Costera, a family canning company from Gijón, carries out a production process that preserves its flavor and juiciness for up to 6 years from the preferred consumption date. Gourmet preserves perfect for your table.