Japanese sardine nigiri

Japanese sardine (Iwashi)

【Nigiri sushi: Hikarimono】
Generally, when people say “iwashi,” they are referring to ma-iwashi. 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 known as】
Japanese pilchard, Spotlined sardine, True sardine

【What is Iwashi】
Iwashi migrate in schools near the surface, from coastal waters around Japan to the open sea. When people refer to “iwashi,” they generally mean maiwashi (Japanese sardine). Maiwashi are caught in large quantities and spoil quickly, so they have traditionally been regarded as an inexpensive, lower-grade fish (known as gezakana). For this reason, few sushi restaurants served iwashi as a topping, particularly high-end sushi restaurants.

Today, however, maiwashi is considered a high-value fish. After the spawning season in December, its fat content drops to a very low level of around 2–3%. However, during its peak season from summer through autumn, its fat content can rise to 25–30%.

【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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(Previous revision date: May 16, 2025; Current revision date: November 12, 2026)