By Harold McGee
Of the many Asian fermentations that mix fish and grains, one of the most influential has been the Japanese narezushi, the original form of modern sushi. The best-known version is funa-zushi, made with rice and goldfish carp (Carassius auratus) from Lake Biwa, north of Kyoto. Various bacteria consume the rice carbohydrates and produce a range of organic acids that protect against spoilage, soften the head and backbone, and contribute to the characteristic tart and rich flavor, which has vinegary, buttery, and cheesy notes. In modern sushi, made with pristinely fresh raw fish, the tartness of narezushi survives through the addition of vinegar to the rice.