Japanese bluefish nigiri

Japanese bluefish (Kuromutsu)

【Nigiri sushi: Shiromi】
Japanese bluefish (Scombrops gilberti), known as kuromutsu in Japanese, was once considered a low-grade fish because its extremely rich, heavy flavor was often regarded as excessive. Although catches were abundant in the past, kuromutsu is now rarely found in supermarkets and is primarily served at high-end Japanese restaurants and sushi bars. Depending on the season, wild kuromutsu can command prices of 5,000 yen or more per kilogram, with large specimens fetching over 10,000 yen per kilogram.

Preparing kuromutsu as yushimo zukuri or yakishimo zukuri allows its natural richness to shine while adjusting its overall flavor. For those concerned about its distinctive odor, yushimo zukuri can be particularly effective. This technique involves pouring boiling water over the skin and immediately immersing the fish in ice water to cool it. This helps remove some of the excess fat and odor from the skin and the layer of fat beneath it. Yakishimo zukuri, in which the skin is seared before the fish is cooled in ice water, is also a commonly used technique. It adds a toasty aroma while bringing out the rich umami of the fat in and beneath the skin.

In the Kanto region, kuromutsu is particularly popular among younger sushi chefs who pay close attention to details such as the temperature of the vinegared rice. To balance its rich, fatty flavor, many sushi restaurants serve kuromutsu with rice seasoned primarily with robust red vinegar. Its relatively tender texture complements the vinegared rice, and when served as nigiri sushi, the fat seems to melt in the warmth of the mouth. Given the recent popularity of prized fatty fish such as nodoguro and kinmedai, it is hardly surprising that kuromutsu has also gained attention as a sushi topping.

【What is Kuromutsu】
Mutsu (Gnomefish) lives in the Pacific Ocean from Hokkaido to Kyushu, in the Sea of Japan and the East China Sea at depths of 200 to 700 meters. It can grow to up to 50 cm. On the other hand, the Kuromutsu (Japanese bluefish) is only found in a very small area from Fukushima Prefecture to the eastern coast of the Izu Peninsula. It grows to be 30 to 80 cm. Mutsu and Kuro-mutsu are extremely similar and normally they are not distinguished, so here we will refer to them both as Kuromutsu.

Incidentally, the term “mutsu” comes from the dialects of the Shikoku and Chugoku regions, where it means “mutsukoi or mutsukkoi,” which basically means ‘greasy’ or “strong-tasting.”

【Trivia】
Kuromutsu were disturbers a long time ago when we were fishing Splendid alfonsino (Kinmedai). And they were not really liked by Edo people who don't really like oily taste. However the price of them went up rapidly when it proved that they are actually really tasty fish. And they are one of those high-quality fish today.

【Substitute fish】
Chilean sea bass: Dissostichus eleginoides
Cardinal Fish or Bigeye: Epigonus telescopus (Risso, 1810): Cardinal Fish is a member of the Yanasemutsu family that lives in the deep waters of New Zealand and is a substitute for Kuromutsu. It has a fine, soft white flesh. It is suitable for miso-grilled or simmered dishes.

【Related contents】
List of White flesh fish (Shiromi)

(Previous revision date: December 22, 2025; Current revision date: October 26, 2026)