Understanding Tuna Grades: Gold Tuna’s Premium Grade No. 9

[In the world of tuna, the highest possible distinction is No. 9.

Only fish that pass rigorous audits of aging, fat distribution, weight, and color earn this grade.

Goldtuna exclusively selects these peak-tier specimens.

This serves to explain the standards of No. 9 and why we insist on such uncompromising quality.]

1. Introduction – The measurable standards of tuna

Few realize that tuna is governed by a strict grading system.

In the world of fine dining, quantitative benchmarks exist to define the quality of Bluefin tuna.

Goldtuna adheres to the most demanding of these: the No. 9 grade.

While we did not create the standard, we were among the first to fully adopt it.

This grade is more than a name; it is the vocabulary of excellence rooted in data.

The No. 9 Grade Distinction

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2. Five Absolute Requirements for Certification

① Temperature and Duration of Aging

The fish undergoes stabilization for 5 to 8 hours at exactly 0°C.

This low-temperature rest minimizes tissue damage and harmonizes the fat and protein.

② Marbling Content

A fat content of 60% or higher is required.

The marbling must be intricate and fine, resembling fallen snow.

③ Selection of Cuts

Limited to the collar and the foremost sections of the fatty belly.

These rare cuts comprise less than 4kg of a single large tuna.

④ Physical Specifications

Only Bluefin tuna weighing over 160kg qualify.

Uniform fat distribution and healthy vascular density are verified.

⑤ Luster and Freshness

The ideal color ranges from vibrant pink to pale rose.

It must maintain a translucent sheen under any light.

No. 9 Grade Tuna Selection

3. The Management System – Trust through data

Every piece of tuna arriving at Goldtuna undergoes a three-step inspection.

(Visual clarity → Textural audit → Color comparison)

The aging process is monitored by digital logs accurate to 0.1°C.

The history of each fish is stored in our database for complete traceability.

We rely on consistency of data rather than the chef's intuition alone.

Tuna is a living creature, but its management must be a science.

The Omakase Special course presentation

4. Why we insist on No. 9

No. 9 is not just "good" tuna; it is tuna that has survived a rigorous filtering process.

Less than 1% of the global catch meets these conditions.

Our tuna is not premium because it is expensive; it is expensive because it is exceptional.

A guest does not need to remember the number.

The moment they taste a single piece, the sensation itself explains the standard.

A handwritten note of gratitude left by a guest

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5. Conclusion – Excellence is never an accident

Quality is determined by structure, not luck.

Aging, marbling, weight, color, and cut—these five criteria are verified by numbers.

Every day, we source No. 9 tuna to prove these standards at the table.

The dignity of a meal is a result of deliberate choices.

"Goldtuna, where No. 9 is the standard."

This is the only information a guest truly needs to trust.

Quality within reach during lunch hours.

→ Is all tuna the same? An exploration of culinary differences (Feb 15, 2025)

→ The conditions of a true destination restaurant, by the owner of Goldtuna (Mar 9, 2025)

→ Among the top three tuna houses in Seoul