Funa-zushi
Japanese: 鮒寿司（鮒鮓）
Made with nigorobuna crucian carp from Lake Biwa, salt-cured and lacto-fermented with cooked rice for months. It is Japan's oldest sushi form and the representative narezushi.
Funazushi is made by gutting nigorobuna carp (keeping the roe), salt-curing, then layering with cooked rice in summer. Lactic acid bacteria convert rice starch into lactic acid, lowering pH to preserve the fish. After months to years of aging, distinctive sourness and rich umami develop. This ancestral form of sushi—the origin of modern nigiri—is a treasure of Shiga, uniting Lake Biwa's bounty with lactic fermentation. Funazushi divides opinions, but in Shiga it is an essential tradition for New Year and celebrations. Young producers have recently emerged, preserving traditional methods while exploring new ways to serve it.