【Reading】むつ

【English Name】Japanese Bluefish

A large deep-sea fish belonging to the family Scombropidae, with the scientific name Scombrops boops. It is widely distributed from the Indo-Pacific to the Atlantic coast of southern Africa, and in Japan it is confirmed in each sea area south of Hokkaido.

Adults are commonly around 60 cm in body length, but among large individuals there are also those that break through the 1 m wall. With a streamlined body shape, large eyes, and a broad mouth, the forward-projecting lower jaw in particular impresses a distinctive appearance. Its body color changes markedly with growth, transforming from the reddish-brown to ochre of the juvenile stage to purplish-black as an adult, with even the interior of the mouth dyed black. Taking rocky reef zones as its main habitat, it forms its living range in the layer at depths of 200 to 700 m. Carnivorous, it actively preys on small fish, squid, and crustaceans.

The spawning period is generally October to March, and at spawning it has the habit of moving to comparatively shallow sea areas at depths in the 100 m range. In winter, when the quality of its flesh reaches the highest level, it is called "kan-mutsu" (cold-season mutsu) and receives high praise from gourmets. Despite being white-fleshed, it is characterized by abundant fat, and its appeal is a melt-in-the-mouth richness. As for the origin of its name, the leading theory holds that adjectives such as "mutsukkoi" (rich) and "numenume" (slimy) are the etymology.

It can be used in a wide range of dishes such as simmering, hot pots, and miso marinade, and is also prized as a material for sashimi and nigiri sushi. Its ovaries are called "mutsugo" and have long been cherished as a rare delicacy with a flavor resembling tarako (cod roe). Confusion easily occurs with the kuromutsu, which is very similar in appearance, but the number of lateral-line scales (mutsu 50-56, kuromutsu 60-68) and the shape of the teeth in the upper jaw serve as important criteria for telling the two apart.