Cutlassfish (Tachiuo) Overview

The cutlassfish (Trichiurus lepturus), known in Japan as Tachiuo (太刀魚),
is a long, silver, sword-shaped marine fish. It is valued both as a food ingredient in Japanese cuisine
and as a target species for coastal and offshore fishing. Its shiny, blade-like body gives it the
nickname “sword fish” in Japanese.

What is Cutlassfish?

Cutlassfish belongs to the family Trichiuridae. It is a predatory marine species
commonly found in temperate and tropical waters. Known for its lean but rich taste,
it plays an important role in Japanese markets, restaurants, and home cooking.

Seasonality and Taste

The peak season for cutlassfish in Japan is from July to October, when its flesh becomes fatty and flavorful.
It has a mild, delicate taste and soft texture, making it suitable for grilling, frying, and sashimi.
Its skin is edible and adds extra aroma when cooked.

Habitat and Distribution

Cutlassfish is widely distributed across the East China Sea, Korean Peninsula, southern Japan,
and Australian coastal waters. Studies indicate population fluctuations depending on season and
sea temperature. According to FAO fisheries data, it is a significant species in East Asian waters.

Names and Etymology

The Japanese name Tachiuo literally means “sword fish,” reflecting its sharp, elongated body.
In English, it is also called Largehead Hairtail or Cutlassfish.
Other names include “beltfish” and “scabbard fish” in some regions.

Taxonomy and Scientific Name

Scientific name: Trichiurus lepturus (Linnaeus, 1758).
Classification: Order Perciformes, Family Trichiuridae.

Basic Information

Average length ranges between 60–120 cm, with some specimens reaching over 200 cm.
Weight typically varies from 500 g to 2 kg. The fish has a compressed body, sharp teeth, and a pointed head.

Ecology and Characteristics

Cutlassfish is a carnivorous predator feeding mainly on smaller fish, squid, and crustaceans.
It is usually found in coastal waters at depths of 100–400 m. Its shiny guanine-coated skin
has historically been used in decorative materials.

Fishing Methods and Regions

In Japan, cutlassfish is caught by longline, trawl nets, and recreational fishing methods such as jigging and tenya.
Popular fishing grounds include Tokyo Bay, Osaka Bay, and the Seto Inland Sea.
It is a prized catch among anglers due to its strength and sharp teeth.

Relationship with Humans

Beyond being a common food source, cutlassfish also appears in local proverbs and cultural references.
It is considered both affordable and high-class depending on its size and freshness.
In markets, larger individuals are often branded as “Dragon-size Tachiuo.”

Cooking and Recipes

Cutlassfish is versatile and appears in many Japanese households and restaurants.
It can be enjoyed fresh, grilled, fried, simmered, or raw. Its delicate flesh pairs well with
soy sauce, miso, and citrus-based seasonings.

How to Fillet and Prepare Cutlassfish

The fish can be cut into fillets, cross-sections, or opened flat. Its long body makes it easy to slice for grilling or sashimi.

Grilled Cutlassfish (Shioyaki)

A traditional and simple preparation, salted and grilled until the skin is crispy and the meat is fluffy.

Braised Cutlassfish

Simmered with soy sauce, sake, and ginger, resulting in a sweet-savory dish that pairs well with rice.

Cutlassfish Sashimi

Fresh slices served raw, often with citrus and soy sauce. Popular in regions with local catches.

Tempura and Fry

Cut into portions, coated in batter, and deep-fried for a crispy finish.

Cutlassfish Stew and Soup

Bones and head are often used in miso soup or broth, providing rich umami flavor.

Western-Style Recipes (Meunière, Tomato Stew)

Lightly floured and pan-fried with butter, or simmered in tomato sauce for a Mediterranean touch.

Korean-Style Braised Cutlassfish

Known as “Galchi Jorim,” braised with chili, radish, and soy sauce in Korean cuisine.

Popular Dishes and Local Specialties

Tachiuo appears in sushi restaurants, izakaya, and coastal markets. In Kansai, it is also enjoyed as pressed sushi.
Local specialties include dried Tachiuo in Shizuoka and “Ryukyu” style marinated sashimi in Kyushu.

Preservation and Freezing

Fresh cutlassfish can be refrigerated for 1–2 days. For longer storage, it is commonly frozen in fillet or cut sections,
keeping quality for up to one month. Mirin-dried and salted versions are popular preserved products.

Processed Products and Regional Brands

Dried Cutlassfish

Sun-dried or grilled versions are sold as souvenirs in fishing towns.

Mirin-Dried Cutlassfish

Sweet soy-marinade dried fillets, widely distributed in supermarkets.

Grilled Skewers and Packaged Foods

Vacuum-packed grilled Tachiuo skewers are available for easy home cooking.

Cutlassfish as Sushi

In sushi culture, Tachiuo is served as nigiri, aburi (seared), or pressed sushi. Its shiny silver skin makes it visually appealing.
It is considered a seasonal delicacy in sushi restaurants.

Nutrition and Health

Cutlassfish is rich in protein, omega-3 fatty acids, and vitamin D. Its lean flesh makes it a healthy choice
for balanced diets. Caution is advised when consuming large predatory fish due to possible mercury accumulation.

Fishing Information and Seasons

Summer to early autumn is the prime season for both commercial and recreational fishing.
Night fishing with lights is a popular method in Tokyo Bay and Osaka Bay.

History, Proverbs, and Trivia

In Japan, Tachiuo has been referenced in Edo-period markets and fishing lore.
Its long, sword-like body led to sayings comparing it to bravery and sharpness.

Photo and Illustration Resources

High-quality cutlassfish images and illustrations are available from fisheries associations,
stock photo libraries, and academic journals for educational and culinary use.

References and Further Reading

Sources incl