【Reading】くろむつ

【English Name】Black Japanese Bluefish

The kuromutsu (Japanese bluefish) is a large deep-water fish belonging to the genus Scombrops in the family Scombropidae. It is given the scientific name Scombrops gilberti (describers: Jordan & Snyder; year: 1901), known as a strongly carnivorous species reaching a maximum body length of nearly 1 m.

The "kuro" (black) in its name was given for the conspicuous blackness of its body color compared with the mutsu. Among fishery workers, the alternate name "karasu" (crow) has been used in some areas. Its distribution spans from southern Hokkaido to central Honshu, characteristically biased further north than the mutsu. Mature individuals make rocky-reef zones at depths of 200-500 m their main living range, preying on small fish, squid, and crustaceans.

Its appearance is very close to the mutsu, requiring care in distinguishing them after capture. As clues for telling them apart, the number of teeth in the upper jaw (9-12 in kuromutsu, 13-15 in mutsu) and the number of scales along the lateral line (60-68 in kuromutsu, 50-56 in mutsu) are useful for identification. The spawning season is around March to May, somewhat later than the mutsu.

The white flesh of the kuromutsu is highly rated for being rich in fat. There is even a theory that the dialect expression "mutsukkoi" (oily) is the origin of the name of the mutsu group as a whole. In sushi it is often served seared (aburi), and it is a fish with a wide cooking range—sashimi, simmered dishes, hot pots, miso-marinated, and more. Its season is winter, before spawning.

From the standpoint of mercury content, the Ministry of Health, Labour and Welfare advises that intake during pregnancy be kept to a guideline of 80 g per serving, twice a week (about 160 g total).