Proteins

Fatty Tuna Belly (Otoro)

The richest, marbled cut of tuna belly that melts as premium sushi.

Otoro is the fattiest, most marbled portion of the bluefin tuna belly, the most prized cut for sushi and sashimi. Its high fat content gives it a buttery, melt-in-the-mouth richness. It is served raw and minimally handled to let the fat speak.

Fatty tuna belly, known as otoro in Japanese, is the most coveted cut of bluefin tuna—the anterior ventral belly muscle that runs beneath the ribs and above the belly wall. This section yields only 3–5% of the entire fish, making it extraordinarily rare. What distinguishes otoro from every other tuna cut is its extraordinary fat content, which ranges from 20–35% by weight and appears as white striations (ashi) threading through pale pink flesh. The fat is firm enough to hold shape when sliced yet dissolves instantaneously on the tongue, delivering an intensely rich, buttery experience with a subtle sweet finish that no other fish replicates.

The quality of otoro depends almost entirely on the degree and uniformity of its marbling. At Tokyo's Toyosu Market, graders distinguish 'top' grade—nearly white with dense, even marbling—from 'first' grade, which shows good marbling with more visible pink beneath. Winter-caught Pacific bluefin (November through February) commands the highest prices because these fish feed voraciously before spawning season to build fat reserves, resulting in the richest possible belly section. Kama-toro, from the thickest part of the gill-plate belly, represents the pinnacle of this already rare cut.

For raw consumption, parasite safety is non-negotiable. Any otoro destined for sashimi must undergo blast-freezing at −20°C for at least 24 hours or −35°C for 15 hours to eliminate parasitic larvae. When sourcing, verify that your supplier follows strict HACCP protocols—this is not optional. At its best, properly handled otoro is a transcendent experience; handled carelessly, it becomes dangerous and loses its defining character within 48 hours of purchase.

Measured in: g
Storage: Fridge

Allergens

Fish

Types & varieties

Kama-toro (kamatoro)

The fattiest cut from the thickest part of the gill-plate belly; the most prized and rarest portion of an already rare cut

Matsutora

Bluefin tuna caught near Matsushima, Miyagi Prefecture; considered among Japan's finest for its exceptional marbling

Miyagi-otoro

From Miyagi Prefecture; highly regarded for fine marbling and buttery texture that melts cleanly on the palate

Barents Sea Bluefin

Norwegian-caught bluefin, increasingly recognized for quality; available July through October

Atlantic Bluefin

Primarily from Mediterranean and Eastern Atlantic waters; major source for European markets, quality varies significantly by fishery and season

Understanding Marbling (Ashi)

The white striations running through otoro flesh are not sinew but pure fat deposits between muscle fibers. This intramuscular fat is what creates the characteristic melt-in-mouth quality—heat from your tongue liquefies the fat before the firmer protein reaches your palate, creating the sensation of pure richness dissolving on contact. The fat should be firm enough to hold its shape when sliced at refrigerator temperature but should begin softening the moment it meets air. Visually, more white and more uniform distribution indicates higher fat content and superior quality. Top-grade otoro appears nearly white with pink barely visible beneath the marbling.

Look for marbling that extends throughout the cut, not just on the surface
Fat should be white or ivory, never yellowed (yellowing indicates oxidation and age)
Press gently—the flesh should spring back, not leave an indent

Sourcing and Supplier Relations

For home cooks, establishing a relationship with a reputable Japanese grocer is essential. Ask when their weekly sashimi shipment arrives and plan your purchase accordingly—fresh otoro loses quality within hours of arrival. For restaurant-quality results, seek suppliers with high sashimi turnover who can verify cold-chain integrity from boat to counter. When purchasing whole or half tunas, inspect for firm flesh that bounces back when pressed, clear eyes (if head-on), and a clean ocean smell rather than any fishy or ammonia-like odor. Never accept otoro that has been previously frozen and thawed for sale as fresh—it will be mushy and lack the characteristic clean fat texture.

Request the catch date and verify blast-freezing history if not buying fresh
Avoid purchasing otoro from general seafood counters without dedicated sashimi handling
Consider joining a buying cooperative for access to auction-grade fish at wholesale prices

Common uses

Premium nigiri sushi—the canonical use where a single piece often serves as the centerpiece of an omakase courseSashimi presentations with minimal accompaniments to showcase the extraordinary fat quality and melt-in-mouth textureLightly seared (aburi) as a transition course, torching just the outer surface so the fat caramelizes while the interior remains rawFinely chopped as a sophisticated hand-roll filling with sushi rice and minimal nori, allowing the richness to bind with the riceGarnished with thin-shaved wasabi root rather than premade paste to honor the quality of the fishTopped onto properly seasoned sushi rice in chirashi-zushi (scattered sushi bowl) presentationsAs a luxurious garnish for clear soups, added at the last moment so the heat barely warms but doesn't cook the fatNot suitable for any cooking method that renders fat—grilling, broiling, or frying destroy the prized texture entirely

Tips & pitfalls

Slice across the grain at a 45° angle into pieces weighing 15–20g for nigiri—too thick and the fat doesn't warm properly on the tongue, too thin and it falls apart
Bring otoro from near-freezing to approximately 15–18°C (59–64°F) before serving; cold fat has no aroma and tastes flat and one-dimensional
Use a sharp, single-bevel yanagiba knife designed for sashimi—any crushing of the delicate fat cells between the marbling ruins the prized melt-in-mouth texture
If sourcing whole, look for firm flesh that bounces back when pressed, clear eyes on whole fish, and a clean ocean smell, not fishy or ammonia-like
Never microwave or cook otoro in any way that generates high heat—the fat renders out, leaving a dry, unpleasant result
Store in the coldest part of the refrigerator, wrapped in paper towels to wick moisture, then plastic wrap, and consume within 48 hours of purchase
For restaurant-quality results at home, buy from a reputable Japanese grocer with high sashimi turnover and ask when their weekly shipment arrives
Avoid using premade wasabi paste—grated fresh wasabi root (hon-wasabi) is the only appropriate accompaniment for premium otoro

Nutrition

No USDA FoodData Central match for Fatty Tuna Belly (Otoro) yet. We surface a per-100 g profile once a generic whole-food entry is matched and verified.

In the shops

Matched grocery products

Tuna Pie
Hacendado · 260 g · Mercadona
€2.90
Tuna Pie
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€4.99
Tuna Loin Paté
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€2.30
Natural Tuna Rondanxa
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€3.25
Yellowfin Tuna Slices
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Terra i Tast Tuna Cake
TERRA I TAST · kg · Bonpreu
€2.99

Good to know

Species: Bluefin tuna (Thunnus thynnus, Pacific bluefin T. orientalis)
Cut Location: Anterior ventral belly muscle, beneath the ribs and above the belly wall
Fat Content: 20–35% by weight; highest of any tuna cut
Color and Texture: Pale pink to ivory with white marbling (ashi); fat is firm when cold but melts at body temperature
Peak Season: Winter-caught Pacific bluefin (Nov–Feb) for superior fat accumulation
Sashimi Safety: Must be blast-frozen at −20°C (−4°F) for 24+ hours or −35°C (−31°F) for 15+ hours to kill parasites
Shelf Life: 2–3 days refrigerated at 0–2°C (32–36°F); deteriorates rapidly beyond that
Typical Price: $60–150+ per kilogram at wholesale markets like Tsukiji/Toyosu

Substitutes

Chutoro (medium-fatty tuna belly) — From the middle section of the belly with 10–15% fat content; the closest substitute offering recognizable richness at roughly half the price
Yellowfin tuna belly (ahi), leaner cut — Not a direct substitute—the fat content is far lower and texture is firmer, but acceptable when bluefin otoro is unavailable or budget-constrained
Spanish mackerel (sawara) belly — High fat content and similar melt-in-mouth quality; different flavor profile (more pronounced fishiness) but a worthy alternative for sashimi presentations
Otoro from yellowfin tuna — Less common but exists in some markets; fat quality and marbling are inferior to bluefin but provide a similar eating experience at a lower price point

Pairs with

Wasabi (hon-wasabi preferred)Shoyu (soy sauce)Sushi rice (shari)Pickled ginger (gari)Sea salt (Maldon or fleur de sel)Yuzu kosho

Also called

Otoro · Toro · Tuna Belly