Japanese sardine nigiri

Japanese sardine (Iwashi)

【Nigiri sushi: Hikarimono】
What is Iwashi?
Iwashi migrates in schools on the surface layer from coasts all over Japan to the open seas. When someone says ‘iwashi’ they are generally referring to ‘maiwashi’. Maiwashi is caught in large volume and loses its freshness quickly, so it is treated as a cheap, lower quality fish (called Gezakana). Therefore in the past there weren’t many sushi restaurants that served iwashi as a topping, especially high-end sushi restaurants. However now it is one of the high-priced fish. Once the spawning season (December) is over, the fat content of maiwashi drops to a very low 2-3% but from summer to autumn when the fish is in-season, the fat content increases to 25-30%.

What does Iwashi (Japanese sardine) nigiri sushi taste like?
Generally, when people say “sardine,” they are referring to the Japanese sardine. Because it is caught in large quantities and loses its freshness very quickly, it was once considered a low-grade fish. As a result, few restaurants consistently keep it in stock as a sushi topping, and it has rarely been used, especially in high-end sushi restaurants.

However, Japanese sardines at their peak season offer exceptional flavor. While their fat content drops to around 2–3% in winter after the spawning season, it increases to 25–30% from summer through autumn. Sardines caught during the rainy season, in particular, are rich in high-quality fat, offering a rich, melt-in-the-mouth umami flavor.

The names vary depending on size: those around 10 cm are called “Koba (小羽),” those around 15 cm are called “Chuba (中羽),” and those over 20 cm are called “Ooba (大羽).” Among these, Chuba sardines caught during the rainy season are considered the highest grade.

However, sardines lose freshness extremely quickly and contain many small bones, so preparation requires a high level of skill. A sushi chef’s deftness in carefully removing the small bones and handling the fish without breaking the flesh directly contributes to the perfection of its flavor.

Furthermore, even when fresh, sardines tend to develop a distinctive aroma from the bloodline and a strong fatty scent. Consequently, great care is taken in the use of condiments. While it is pleasant to enjoy them with grated ginger or asatsuki for a refreshing taste, some restaurants also place green onions between the rice and the fish. The sulfur-based aromatic compounds in green onions gently envelop the sardine’s characteristic aroma, leaving a clean, refreshing aftertaste.

Also called Japanese pilchard or Spotlined sardine or True sardine.

【Temperature of vinegared rice (shari) and sushi toppings】
36℃/20～23℃

【Substitute fish】
European sprat: Sprattus sprattus (Linnaeus, 1758)
South American pilchard: Sardinops sagax
European pilchard: Sardina pilchardus

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(Updated on May 16, 2026)