What is the difference between bluefin tuna and yellowfin tuna?

Bluefin is a larger, fattier, and more intensely flavoured fish than yellowfin. The flesh is richer, more marbled, and has a depth of flavour that yellowfin doesn't match — particularly in the otoro (belly) cuts. Bluefin is the tuna prized above all others in Japanese sushi culture. Yellowfin is leaner, cleaner, and more affordable — an excellent fish in its own right, but a different eating experience. We carry both: Fuentes Bluefin on this page, and yellowfin tuna steaks and saku blocks in our Fish & Crustacea collection.

What is ike jime and why does it matter?

Ike jime is a Japanese dispatch technique where the fish is killed instantly with a spike to the brain, then the spinal cord is destroyed to prevent nerve signals from degrading the flesh. This stops stress hormones and lactic acid from building up in the muscle, which directly affects flavour, texture, and shelf life. Fish dispatched with ike jime have cleaner taste, firmer texture, and better colour retention than conventionally caught fish. All Fuentes bluefin tuna is dispatched using this method.

What is the difference between akimi, chutoro, and otoro?

These are the three main cuts of bluefin tuna, defined by fat content and location on the fish. Akimi is the lean loin — deep red, meaty, and clean. Chutoro is the middle section between loin and belly — medium fat, silky, and balanced. Otoro is the belly — the fattiest, most prized cut with a buttery, melting texture. Each fish yields only a small amount of otoro, which is why it commands the highest price.

Which cut should I choose?

For tartare and tataki, akimi is the best choice — its clean, lean character works perfectly when seared or diced. For sashimi and nigiri where you want richness, otoro delivers the full bluefin experience. Chutoro sits between the two and is considered by many chefs to be the most balanced cut. If you're new to bluefin, an akimi saku block is a good starting point.

Is your bluefin tuna sustainable?

Our bluefin comes from Fuentes, who use sustainable fishing techniques and operate under regulated quotas across the Mediterranean. Fuentes have been working with bluefin tuna for over fifty years and operate facilities across six countries. Mediterranean bluefin tuna stocks have shown significant recovery in recent years following strict international quota management. Our season runs from September to May.

Can I eat bluefin tuna raw?

Yes. Our bluefin tuna is AAA grade and suitable for raw consumption — sashimi, sushi, tartare, and crudo. The fish is blast frozen to –50°C immediately after processing, which eliminates any parasites present in the flesh and meets UK food safety requirements for serving fish raw. For otoro and other fatty cuts, bringing the fish to just below room temperature before serving — a few seconds with a blowtorch or a flash in a hot dry pan — releases the full flavour of the fat.

Why does tuna sometimes darken after defrosting?

Oxidisation. Red-fleshed fish like bluefin is stored at –50°C to preserve the vibrant colour. Once thawed and exposed to air, the surface can shift from bright red to a deeper brownish tone. This is natural and doesn't mean the fish has spoiled. To minimise it, remove from vacuum packaging and place on a plate lightly covered with cling film. Use the same day you defrost.

How should I defrost bluefin tuna?

Remove from vacuum packaging, place on a plate, cover lightly with cling film, and defrost in the fridge. Use the same day for the best colour, flavour, and texture. Do not defrost in water or at room temperature — both cause uneven thawing and accelerate oxidisation.

What is a saku block?

A saku block is a precision-cut rectangular portion of tuna, trimmed to a uniform shape for clean, even slicing. The word "saku" comes from the Japanese term for a trimmed loin block used in sushi preparation. Our saku blocks are ready to slice straight from defrosting — no further trimming needed. Available in both akimi (loin) and otoro (belly).

Bluefin Tuna

Bluefin Tuna Otoro Slice

From £35.00

Bluefin Tuna Otoro Saku Block

From £30.00

Bluefin Tuna Akimi Saku Block

From £25.00

OTORO

Otoro is the most prized and comes from the belly, which is the fattiest part of the tuna, The most legendary cut of tuna, and one of the most highly prized by lovers of fine cuisine. With a pinkish colour and silky, highly delicate texture, the belly, known as “Otoro”, is found at the base of the lower loin and contains the highest fat level.

TUNA TATAKI

This very simple recipe works as a delicious starter or can be served with addition of forbidden rice, steamed pak choi and baby corn as a fantastic light and healthy main course.

In this recipe we used the Akami cut of Bluefin Tuna which is the lean red meat from the main body of the tuna. It is also possible to use either the Otoro (the fattier belly section which is intensely rich and melt in the mouth) or the Chūtoro (which is a combination of the Akami lean red meat and the fattier belly, found near the skin on the belly and back).

RECIPE

TUNA TARTAR

A brasserie classic, tartare should always be made with the best quality sushi grade tuna, such as our exceptional Bluefin Tuna Akimi Saku Block. This simple dish is so easy to prepare, but makes a really impressive summery lunch.

RECIPE

Buy Premium Bluefin Tuna Online in the UK

FINE & WILD carries AAA-grade Mediterranean Bluefin Tuna from Fuentes, the global leader in bluefin tuna production with over fifty years of experience and a reputation built on supplying the Japanese market — the most demanding and knowledgeable tuna market in the world. All Fuentes bluefin are wild adult fish, caught using sustainable fishing practices and dispatched using the Japanese ike jime technique to preserve the quality of the flesh from the moment of harvest. Every cut is fully traceable from sea to table.

Our bluefin tuna is cut in-house and blast frozen to –50°C to maintain the highest quality and food-safe standards. The wild-caught Mediterranean season runs from September to May.

About Fuentes

Ricardo Fuentes e Hijos is a family business based in Cartagena, Spain, with operations across Spain, Portugal, Morocco, Malta, Italy, and Tunisia. They have been working with bluefin tuna for over half a century and are now the global market leader. Their fish have been the preferred choice on the Japanese market for more than thirty years — a distinction that speaks directly to the quality of their product, given Japan's unrivalled standards for tuna.

Fuentes use sustainable fishing techniques and have full control over their supply chain. Every fish is dispatched using ike jime, a Japanese method that immediately kills the fish with a spike to the brain, preventing stress and lactic acid build-up in the flesh. This produces cleaner flavour, better texture, and longer shelf life compared to conventional methods. Each product carries a traceability label tracking the cut from sea to table.

Bluefin Tuna Cuts Explained

Bluefin tuna is butchered into distinct cuts, each with different characteristics. Understanding the cuts helps you choose the right product for your preparation.

Akimi — The Loin

Akimi is cut from the main loin of the tuna — the large, lean muscle that runs along the back of the fish. It's deep red in colour, low in fat, high in protein, and the most commonly used cut. The flavour is clean, meaty, and direct. Akimi is the best choice for tartare, tataki (seared rare), nigiri sushi, and any preparation where you want the pure, concentrated taste of bluefin without the richness of the fattier cuts. Our Akimi Saku Block is a precision-cut rectangular portion, ready for slicing.

Chutoro — Medium Fatty Tuna

Chutoro comes from the area between the loin and the belly — the transition zone where lean red meat meets the fat of the belly. "Chu" means "middle" in Japanese, and that's exactly what this cut delivers: more richness and sweetness than akimi, with a slightly pinkish colour graduating to deeper red, but without the full intensity of otoro. The texture is silky yet still has structure. Chutoro is outstanding as sashimi, sushi, or lightly seared. It's the cut many chefs consider the most balanced and versatile part of the bluefin.

Otoro — The Belly

Otoro is the most prized cut of bluefin tuna in the world. Taken from the belly — the fattiest section of the fish — it has a pinkish colour, a silky, almost melting texture, and an intensely rich, buttery flavour. Each fish yields only a small amount of otoro, which accounts for both its scarcity and its price. This is the undisputed star of raw preparations: sashimi, nigiri, and tartare. Some chefs also sear it briefly to create a roasted crust with a molten centre. Otoro is best not served ice-cold — a few seconds with a blowtorch or a flash in a very hot dry pan warms the fat just enough to release its full flavour and improve the texture. We carry otoro as both individual slices and saku blocks.

Bluefin Tuna Cuts at a Glance

Cut	Location	Fat Content	Character	Best Preparation
Akimi	Loin (back)	Low	Deep red, lean, clean, meaty	Tartare, tataki, nigiri, seared
Chutoro	Between loin and belly	Medium	Pink to red, silky, sweet, balanced	Sashimi, sushi, light sear
Otoro	Belly	High	Pale pink, buttery, melting, rich	Sashimi, nigiri, brief sear

How to Prepare Bluefin Tuna

Bluefin tuna is at its best raw or barely cooked. The quality of Fuentes bluefin means the fish needs very little done to it — the flavour and texture speak for themselves.

Sashimi and sushi: Slice akimi or otoro against the grain into clean, even pieces. Use a sharp, wet knife. Serve with soy sauce, freshly grated wasabi, and pickled ginger. The difference between good and great sashimi is almost entirely about the quality of the fish — this is where premium bluefin earns its reputation.

Tataki: Season a saku block of akimi with salt and sear in a ripping hot pan for 10–15 seconds per side, leaving the centre completely raw. Slice thinly and serve with ponzu, sesame, and spring onion. See our Bluefin Tuna Tataki recipe for a full method.

Tartare: Dice akimi finely and dress with soy, sesame oil, lime, and a touch of chilli. Serve with avocado and a spoonful of caviar for something special. See our Tuna Tartare recipe.

Freezing & Defrosting Bluefin Tuna

All bluefin tuna is stored at –50°C and shipped in insulated packaging with ice packs via express courier service. Beyond preserving colour, flavour, and texture, freezing at this temperature is what makes raw consumption safe — it eliminates any parasites that may be present in the flesh, which is a requirement for fish served raw in the UK. This is standard practice across the sushi industry worldwide and is one of the reasons premium tuna is always blast frozen at source.

To defrost, remove the tuna from its vacuum packaging and place on a plate lightly covered with cling film. Defrost in the fridge and use the same day for the best colour, texture, and flavour. Do not defrost in water or at room temperature. Oxidisation can cause the surface to darken once exposed to air — this is natural and does not indicate spoilage, but careful handling minimises it.

Buying Bluefin Tuna Online in the UK

FINE & WILD delivers bluefin tuna across the UK via next-day express courier service. All tuna is shipped in insulated packaging with ice packs to maintain temperature. Orders placed before 2pm are dispatched the same day — select your preferred delivery date at checkout. For orders over £225, weekday delivery is complimentary.

Our Mediterranean bluefin season runs from September to May. If a product is listed on this page, it's available to order now.

Frequently asked questions

What is the difference between bluefin tuna and yellowfin tuna?

Bluefin is a larger, fattier, and more intensely flavoured fish than yellowfin. The flesh is richer, more marbled, and has a depth of flavour that yellowfin doesn't match — particularly in the otoro (belly) cuts. Bluefin is the tuna prized above all others in Japanese sushi culture. Yellowfin is leaner, cleaner, and more affordable — an excellent fish in its own right, but a different eating experience. We carry both: Fuentes Bluefin on this page, and yellowfin tuna steaks and saku blocks in our Fish & Crustacea collection.
What is ike jime and why does it matter?

Ike jime is a Japanese dispatch technique where the fish is killed instantly with a spike to the brain, then the spinal cord is destroyed to prevent nerve signals from degrading the flesh. This stops stress hormones and lactic acid from building up in the muscle, which directly affects flavour, texture, and shelf life. Fish dispatched with ike jime have cleaner taste, firmer texture, and better colour retention than conventionally caught fish. All Fuentes bluefin tuna is dispatched using this method.
What is the difference between akimi, chutoro, and otoro?

These are the three main cuts of bluefin tuna, defined by fat content and location on the fish. Akimi is the lean loin — deep red, meaty, and clean. Chutoro is the middle section between loin and belly — medium fat, silky, and balanced. Otoro is the belly — the fattiest, most prized cut with a buttery, melting texture. Each fish yields only a small amount of otoro, which is why it commands the highest price.
Which cut should I choose?

For tartare and tataki, akimi is the best choice — its clean, lean character works perfectly when seared or diced. For sashimi and nigiri where you want richness, otoro delivers the full bluefin experience. Chutoro sits between the two and is considered by many chefs to be the most balanced cut. If you're new to bluefin, an akimi saku block is a good starting point.
Is your bluefin tuna sustainable?

Our bluefin comes from Fuentes, who use sustainable fishing techniques and operate under regulated quotas across the Mediterranean. Fuentes have been working with bluefin tuna for over fifty years and operate facilities across six countries. Mediterranean bluefin tuna stocks have shown significant recovery in recent years following strict international quota management. Our season runs from September to May.
Can I eat bluefin tuna raw?

Yes. Our bluefin tuna is AAA grade and suitable for raw consumption — sashimi, sushi, tartare, and crudo. The fish is blast frozen to –50°C immediately after processing, which eliminates any parasites present in the flesh and meets UK food safety requirements for serving fish raw. For otoro and other fatty cuts, bringing the fish to just below room temperature before serving — a few seconds with a blowtorch or a flash in a hot dry pan — releases the full flavour of the fat.
Why does tuna sometimes darken after defrosting?

Oxidisation. Red-fleshed fish like bluefin is stored at –50°C to preserve the vibrant colour. Once thawed and exposed to air, the surface can shift from bright red to a deeper brownish tone. This is natural and doesn't mean the fish has spoiled. To minimise it, remove from vacuum packaging and place on a plate lightly covered with cling film. Use the same day you defrost.
How should I defrost bluefin tuna?

Remove from vacuum packaging, place on a plate, cover lightly with cling film, and defrost in the fridge. Use the same day for the best colour, flavour, and texture. Do not defrost in water or at room temperature — both cause uneven thawing and accelerate oxidisation.
What is a saku block?

A saku block is a precision-cut rectangular portion of tuna, trimmed to a uniform shape for clean, even slicing. The word "saku" comes from the Japanese term for a trimmed loin block used in sushi preparation. Our saku blocks are ready to slice straight from defrosting — no further trimming needed. Available in both akimi (loin) and otoro (belly).
How is bluefin tuna delivered?

All bluefin tuna is stored at –50°C and shipped in insulated packaging with ice packs via express courier service. Orders placed before 2pm are dispatched the same day — select your preferred delivery date at checkout. On arrival, transfer straight to the freezer, or place in the fridge if you plan to use it the same day. For orders over £225, weekday delivery is complimentary.

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