Akamutsu Sushi
A Comprehensive Overview of Blackthroat Seaperch in Japanese Sushi Cuisine

The blackthroat seaperch or rosy seabass is called akamutsu in Japan. The term mutsu (むつ) comes from the meaning of mutsukkoi (むつっこい, Tukushima dialect) and means in other words “greasy” or “strong in taste”. Besides the name akamutsu it also carries the very common name nodoguro (喉黒), which is similar to its English name blackthroat. Akamutsu belongs to the family of lantern bellies and is highly valued in Japan as a premium seafood and sushi ingredient. Some connoisseurs refer to its meat as “white toro”, which is said to be in no way inferior in taste and texture to the fatty meat of tuna.

Akamutsu or nodoguro owes its first-class reputation as a gourmet fish to its remarkable high fat content. Under its skin is a distinctive layer of fat that gives the whitish meat a certain sweetness, hence its nickname “white toro”. Whether raw or cooked, its meat has a unique and elegant taste. The meat is soft and has a wonderfully full-bodied umami taste. It harmonizes very well with sushi rice and is therefore appreciated not only as sashimi but also as hand formed sushi (nigiri).

Akamutsu is very tasty regardless of the season, but the best season is considered to be late winter to spring, before it spawns in late summer. The fish is fatty regardless of the season and is popular throughout Japan, especially in urban areas.

In Hamada, a city in Shimane Prefecture on the Sea of Japan, akamutsu is known as nodoguro, a local specialty that is also regularly mentioned in tourist guides. Its name nodoguro, loosely translated as “blackthroat”, is due to the dark coloring on the back of its mouth. Akamutsu is mainly caught in the Sea of Japan, the side of Japan facing away from the Pacific Ocean, and is found along the coast from Toyama to Shimane. It is appreciated as a regional delicacy throughout the Hokuriku region.

Akamutsu lives at sea depths of 100 to 600 m and feeds mainly on smaller fish as well as crustaceans and molluscs. The usual length is 30 cm, with a maximum of 40 cm. Its range extends from the Sea of Japan across the western Pacific to Australia.

It is characterized by its compact body, which is covered by a silver-grey to pinkish shimmering skin. The skin may be slightly reddish in places, giving it a hint of color. Particularly striking are the large, round eyes, which form a strong contrast to the rest of the body with their orange to red irises. The gills are bright red, which also indicates the freshness of the fish. The fins of the akamutsu are thin and delicate. Their color is red-orange and brightens towards the tips.

Akamutsu is considered sensitive to changes in its living conditions. Fluctuating water temperatures and changes in the supply of food are said to have a significant impact on the quality of the catch. Top specimens of akamutsu are traded at comparatively high prices, it is not unusual for particularly good specimen to achieve prices of up to over ¥10,000 (≈ 95 USD) per kilo.

In July 2013, a research group from the Nihonkai-ku Fisheries Research Institute announced that akamutsu had succeeded in being raised in aquaculture for the first time, allowing them to be transferred to their natural habitat. In February 2017, it was confirmed that one of the released akamutsu juvenile fish was able to survive in the wild. The specimen was found as a by-catch in the net of a shrimp fisher. The discovery raises hopes for a more stable market supply and the protection of natural stocks. On the other hand, it was also observed that there are very few females among the adult fish raised by artificial insemination. These and other aspects are still the subject of current research.