Kaz Matsune
- Jan 11
- 6 min read

All about Tuna (maguro) for sushi

A brief history: When did Tuna ascend to its Iconic?

In Edo-Mae style sushi, "Maguro," or Tuna, reigns as the king of sushi ingredients. When I say "King," I mean it from the perspective of a sushi chef.

It wasn't until I became a sushi chef that I understood this. A sushi bar without Maguro is akin to a steakhouse devoid of steak. Tuna nigiri is the centerpiece of the omakase course - it is the protagonist, the hero of the narrative.

Without Tuna, there's no omakase. No hero, no story.

At first, I found it hard to grasp this concept.

"Why can't you just run a sushi bar without Tuna? Why is it a necessity?" I kept questioning.

Eventually, I learned that the answer was rooted in the history of the Japanese's fondness for Tuna, particularly Toro, the fatty Tuna.

Japanese did not always consume Raw Tuna, let alone cooked Tuna. There are several reasons why large Tuna consumption didn't commence until the mid-Edo period, 1603–1868.

Some historians assert that evidence points to the Japanese catching Tuna around 10000–300 BC. However, the capture of such large fish carried many risks. Tuna can weigh as much as 180kg/400lbs, necessitating larger boats and more crew members. It also meant traveling far to the outer ocean. Why risk your life when smaller fish can be caught with less effort? Even if you successfully captured Tuna, the absence of refrigeration made Tuna undesirable. What's the point of catching a big fish if you can't consume it?

The name also discouraged Tuna consumption.

The Japanese used to refer to Tuna as Shibi, a term that sounds like Day of the Dead. Consequently, most people consider it unlucky to eat Tuna. The Japanese favored Tai/Sea Bream over Tuna because "Tai" rhymes with "celebration." Tai was a smaller fish — significantly smaller, with a length of around 50～70cm (20–28 inches). It was easier to catch than Tuna.

A New Era for Tuna and Toro

The Edo Period, Tokyo Around 1830, Edo/Tokyo experienced a large Tuna catch, which lowered its price. Since Tuna became so affordable, some sushi restaurants decided to experiment with it, resulting in its growing popularity. Initially, Tuna was served in a style known as "Zuke" — a soy-marinated Tuna nigiri. Marinating it in soy sauce allowed the tuna to last longer without refrigeration, and it also introduced a unique flavor to the tuna. Up until that point, Tuna was either grilled or cooked, and was deemed unpalatable.

A Change in the Japanese Diet

Although Tuna had become a popular sushi ingredient, the belly was usually discarded. Marinating Tuna belly in soy sauce didn't alter its taste due to its high-fat content. The popularity of Toro, Tuna belly, started to rise around 1930 – 1960. The exact reason for its surge in popularity remains unclear, but one theory attributes it to the change in the modern Japanese diet — a growing preference for "fattier" foods.

Another theory suggests that advancements in refrigeration technology allowed for the extended storage of Tuna, especially toro. Toro's popularity began to increase, and prices started to climb. Many sushi enthusiasts began to view it as a premium sushi ingredient. The Japanese started to regard Toro as the "king" of sushi ingredients. Sushi became one of Japan's major culinary exports to the US, Europe, and Asia, where it had been unavailable until recent years.

Sushi lovers outside of Japan followed suit, regarding Toro as a premium sushi fish.

Fishermen outside of Japan began to see more value in Tuna belly, which they had previously discarded, much like Japanese fishermen about 250 years ago. As the popularity of Sushi grew worldwide, so did the popularity of Toro.

Tuna Auctions, Media Coverage, and Price Hikes

If you're a sushi aficionado, you've probably heard about the Tokyo Fish Market and their annual Tuna auctions. Much like the Edo people who paid no attention to Maguro, no news media reported this event until recently. Most Japanese weren't even aware of its existence.

Things began to change in 2001 when a Tuna from Oma was priced at JPN ¥20 million (Approx. US$ 170,000). Japanese News media began to report this high Tuna price, mentioning "Oma" – a small town in Aomori that most Japanese had never heard of before. Oma Tuna fishermen used longline over the troll and the gillnet fishing method. Longline fishing caused less damage to the Tuna, but it is a more perilous fishing method.

Media coverage on Oma Tuna Fishermen intensified. In 2007, a TV drama "Tuna," featuring famous actor Tetsuya Wataru, was produced with a budget of US$ 10 million, funded by the Oma fishery organization and the city of Oma. Thanks to the TV show, Tuna from Oma became a branded product, akin to Kobe Beef, which contributed to the higher price for Tuna and Toro.

The Rivalry Between Itamae Zushi and Sushi Zanmai

Another factor contributing to the price surge was the competition between two sushi restaurant owners; Ricki Chen of Itamae Zushi and Kiyoshi Kimura from Sushi Zanmai. In 2008, Ricki Chen became the first non-Japanese to win the bid for the new year's Tuna auction at the price of JPN ¥6.7 million (about US$600,000). The Tuna was served at Chen's restaurant in Hong Kong.

This caught the media's attention. Chen kept winning the bid four years in a row over Kiyoshi Kimura of Sushi Zanmai. The contest between Chen and Kimura contributed to the rise of the Tuna price every year. There was a rumor that someday, the Tuna price would surpass one million dollars. In 2013, Kimura made international news headlines for winning the Tuna auction for US$1.3 million. He is known as the "Tuna King" for winning seven consecutive bids between 2012 – 2017.

Types of Tuna for sushi

Tuna is called Maguro in Japanese. There are mainly three types of tuna when Japanese and sushi chefs refer to as Maguro. They are yellowfin tuna, big eye tuna and and Bluefin tuna.

So, what are the differences and how can you tell?

Appearance

(Image from Wikepedia)

Yellowfin is most notable that the tail fin is yellow.

Size

Yellowfin being the smallest of tuna. Bluefin gets the biggest. Ave. size

The bigger the fish, the wider its grains are. This is one way to tell between yellowfin and blue fin.

Bluefin tends to have deeper dark red color compared to yellowfin. Because of their size, Bigeye and Bluefin accumulate more fat on their stomach, which turns its meat more pink red color. This, as many of you know are called Toro.

The most noticeable difference between these three is the width of the grain. Because Yellowfin being the smallest and Blue Fin being the biggest, if you compare them you can see a difference.

Here is a picture of a yellowfin tuna.

Here is Big Eye.

Lastly, Blue Fin.

If you look closely and compare three, the width between the grains of Blue Fins is the widest.

Taste

It’s hard to tell the difference between yellowfin over bigeye, and bigeye over bluefin. But there is a significant difference between yellowfin and Bluefin. Bluefin tends to have more “Tuna” flavor – rich in iron.

Bigeye and Bluefin both have Toro, tuna belly. Bluefin has more fat than Bigeye.

Price

Because its taste and especially Toro, Bluefin is priced higher than Yellowfin and Bigeye. If you ever read on the news about Tuna sold for some two million US dollars, they are Bluefin. Be mind that price is from New Year’s day auction, which is overpriced bid. Regular prices are lot cheaper than the new year’s auction.

How Do You Prepare Tuna for Sushi?

For Edo•Mae (Tokyo) Style Sushi Restaurants, tuna is the definitive fish that showcases their quality, style, and artistry. The selection of tuna is a critical task for sushi chefs when visiting the fish market. It takes center stage in the "omakase," comparable to the main dish in a French or Italian course meal.

Tuna is synonymous with a sushi restaurant, and for sushi chefs, a sushi establishment without Maguro/Tuna is inconceivable. Here are the detailed steps for making tuna sushi, both nigiri, and rolls:

1. Choose the Right Tuna

Each part of the tuna has different qualities and prices, with "Red" meat (A, B, C) being the least fatty and Fatty Tuna Belly (Toro) (D, E) being the most prized. D is the Fattiest Tuna Belly (O-Toro), while E is the Medium Fatty Tuna Belly (Chu-Toro). The tail section (C&F) contains the least fat.

Here is a diagram showing parts of tuna.

Red Meat: A, B, C F

Toro (Fatty Tuna Belly): D, E

Price (high to low): D, E, B, A, C&F

(Image Courtesy of Australian Southern Bluefin Tuna Industry Association)

Here is a block of tuna, close to "E" in the diagram.

Image Courtesy of Australian Southern Bluefin Tuna Industry Association

2. Cut into Blocks (Saku)

To prepare the tuna for sushi, it needs to be cut into small blocks known as "Saku." The cutting process involves following yellow and black lines on the tuna, resulting in various-looking pieces.