If you ask people around the world what their favorite fish is, the answer is sure to be salmon. Its flesh is tender and fatty, with few small bones, and its color is appetizing. But we don’t think most people around the world pay much attention to the type of salmon they eat. This is not surprising, since people do not have the habit of eating many kinds of fish in their daily lives. In Japan, it is common for the species offered to change with the seasons, even among fish of the same family. We sometimes sense that the season has changed based on the change in fish species. For example, seeing a Salmon (Chum, Keta, or Dog salmon) moving up the river, one senses that it is autumn.

This article explores salmon, for which we were able to confirm statistical data. Also, see below for the differences between trout and salmon.
Trout vs. Salmon: What’s the Difference?

Global demand for salmons is strong and production is growing rapidly. Currently, the global production of salmon is over 5 million tons/year. Of this, more than 4 million tons are farmed, of which roughly 3 million tons are Atlantic salmon and 1 million tons are Rainbow trout. The salmon that people around the world say they love are Atlantic salmon and Rainbow trout.

Atlantic salmon is produced in Norway, the United Kingdom, Ireland, the Faroe Islands, Iceland, Canada, the United States, Australia, and Chile. Trout salmon (Rainbow trout) is produced in Norway, Finland, Sweden, Denmark, England, Ireland, Turkey, and Chile.

Although production is low, King salmon, Silver salmon, Cherry salmon, and Brown trout are also commercially farmed. King salmon is a very delicate fish and can only be found in areas with clean water. For this reason, it is difficult to farm, and King salmon accounts for less than 1% of all salmon farmed in the world. New Zealand, Canada, and Chile are the only countries that have succeeded in commercial farming of King salmon. In New Zealand, which is a rare example from a global perspective, no antibiotics are given to the fish. Silver salmon is farmed in Peru, Japan, and other countries, with a yearly production of over 20 tons. It is used as a standard side dish for bento (lunch box) in Japan. Cherry salmon is farmed only in Japan and does not reach 30 tons/year. Masu zushi, a famous specialty of Toyama Prefecture, is made from cherry salmon.

On the other hand, the catch of wild salmon has remained flat for the past 40 years at around 1 million tons/year. More than 90% of the catch consists of six species: King or Chinook salmon, Chum, Keta or Dog salmon, Pink or Humpback salmon, Silver or Coho salmon, Red or Sockeye salmon, and Steelhead trout (Rainbow trout).

Salmon mainly caught in Japan are Chum salmon (Japanese name: Sake, Akizake, Shirozake), Pink salmon (Japanese name: Karafuto-masu), King salmon (Japanese name: Masunosuke), Cherry salmon (Japanese name: Sakura-masu).

The main production areas are Hokkaido, Aomori, Iwate, Miyagi, and Niigata. Red salmon (Japanese name: Benizake) and silver salmon (Japanese name: Ginzake) are rarely caught only in Hokkaido. The catch of chum salmon, which used to be over 100,000 tons/year, has been drastically reduced to less than 50,000 tons/year. On the other hand, Alaska and Russia have recorded catches of over 400,000 tons/year and can be said to have good catches.

However, whether it is farmed or natural salmon is not even a subject of debate, except among some chefs and Japanese. In our opinion, the decision of whether to use farmed or wild should be based on the type of dish to be cooked.

From here, we get down to business.

It has long been said that pink salmon, the most abundant salmon caught in Japan, is not suitable for nigiri sushi. This is not true. It is simply because salmon in good condition was difficult to obtain in the past due to the lack of a well-developed distribution system. As proof of this, migratory pink salmon is highly valued for its rich flavor and fat. On the other hand, pink salmon that have gathered to spawn have lost their fat and are tasteless. This is a common story for all salmon.

In Japan, King salmon, Cherry salmon, farmed Atlantic salmon and Rainbow trout, and Chum salmon, which was born in Russian rivers and migrates along the Hokkaido coast, are used as sushi toppings (ingredients). There was a time around 1980 when sushi chefs used to serve red salmon, which he named Beni-toro, but there is no sign of it now. And we rarely hear of Chum salmon returning to the river where it was born in the fall to be made into Nigiri sushi. Worldwide, only a few countries, such as Russia, Canada, and Alaska in the United States, use wild pink salmon, silver salmon, and red salmon as Nigiri sushi.

We can say with certainty that Edomae Sushi restaurants do not use any salmon. As time goes by, some restaurants have begun to offer King salmon, Chum salmon, Cherry salmon, Biwa trout, and other rare sushi toppings as their main selling point, but only a few of them do so.

Chum salmon originally return to Japan in the fall, but those migrating off the coast of Japan out of season are called Keiji, Tokishirazu, and Mejika to distinguish them. The mother river is in Russia. Chum salmon originally return to Japan in the fall, but those migrating off the coast of Japan out of season are called Keiji, Tokishirazu, and Mejika to distinguish them. These are rarely found in some high-end sushi restaurants, as they have a fresh flavor and fat that is ideal for nigiri sushi. Of course, they are also delicious in other dishes. However, it should be frozen once to kill Anisakis and other fish before making sushi. This is one of the reasons why salmon has been avoided as a sushi topping.

On the other hand, Atlantic salmon and Rainbow trout (known as Salmon trout or Trout salmon) are farmed at sea, exported without ever being frozen, and used for sushi at conveyor-belt sushi restaurants. The fish is already processed into fillets, so the chef only needs to remove the skin.

As a side note, salmon farming is said to have less environmental impact than other fish species. And from the perspective of the SDGs, we are moving from sea farming to land-based aquaculture. In addition, farmed salmons are being actively improved and blended with different species.

Now you may know what kind of salmons you are eating. For your reference.

Related contents:
Learn more about salmon

How salmon fillet are made in factory

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The Japanese name for the blue rainbow trout is Cobalt masu, derived from its blue body color. Blue rainbow trout is a mutation in the hatchery production of rainbow trout. This fish lacks the middle lobe of the pituitary gland. This resulted in blue body color. This rare genetic glitch has occurred only in rainbow and brown trout. It is said that one blue rainbow trout is born for every ten of thousand rainbow trout. This trait is inherited recessively. It does not reproduce and is susceptible to disease. Therefore, although it has a beautiful body color, it is difficult to produce in large numbers.

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Revision date: April 8, 2023

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There is a Rainbow trout with yellow body color.

This is the Albino rainbow trout.

The Albino has no pigmentation. Other Albino fish have a white body color, but the Rainbow trout has a yellow body color. Since its first discovery in 1956 at the Fisheries Experiment Station in Nagano Prefecture, Japan, experiments conducted by crossbreeding Albino with other Albino or Albino with ordinary Rainbow trout have shown that it is genetically dominant. Pure descendants of the Albino are now being produced in aquaculture farms throughout Japan.

Albino is rarely found in the normal production of Rainbow trout in aquaculture farms. Albino is a mutation of the Rainbow trout that lacks tyrosinase (An enzyme that breaks down tyrosine, a type of amino acid, to produce melanin). This prevents the production of melanin, a black pigment, and causes the trout to turn yellow. The yellowish coloration is thought to be due to the other pigments that remain after the melanin-black pigment is gone.

Normal Albino is genetically recessive, so if both parents are not Albino, their offspring will not be Albino. However, Albino rainbow trout is dominant, so if either male or female parent is an Albino, their offspring will be born as an Albino.

Neither the albino rainbow trout nor the blue rainbow trout is a protective color, so if it were to occur in nature, it would have little chance of surviving due to bird damage.

Albino rainbow trout has little edible value but is released for recreational fishing because of its scarcity. In fish farms, it is sometimes used as a visible indicator of growth. There may be some differences in taste, smell, and texture, but these are within the range of individual differences. And Sushi chefs do not use Albino rainbow trout for sushi.

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Revision date: April 7, 2023

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What is White spotted Char (Iwana)?

The Iwana group is divided into four subspecies, with body color and spots varying from region to region. The Ezo Iwana (Salvelinus leucomaenis (Pallas, 1814)) is distributed in Yamagata Prefecture, Chiba Prefecture and northward, Hokkaido to Kamchatka, Sakhalin, and elsewhere. The Yamato Iwana (Salvelinus leucomaenis japonicus (Oshima, 1938)) is distributed along the Pacific coast of Honshu west of the Sagami River in Kanagawa Prefecture, the Kii Peninsula, and the rivers flowing into Lake Biwa. The Nikko Iwana (Salvelinus leucomaenis pluvius (Hilgendorf, 1876)) is distributed throughout Honshu north of the Fuji River in Yamanashi Prefecture and the Hino River in Tottori Prefecture. The Gogi (Salvelinus leucomaenis imbrius (Jordan and McGregor,1925)) is distributed in the Chugoku region west of the Yoshii River in Okayama Prefecture and the Ibo River in Tottori Prefecture. Although all are land-locked, the Ezo Iwana has a descending sea-run type, the Amemasu (アメマス). However, there is one species.

The White-spotted Char (Iwana) is characterized by its low body height, long and slender body, fine scales, whitish spots on the body that are lighter than the body’s natural color, and white anterior margin of the pectoral and anal fins. It lives in the uppermost reaches of mountain streams and is separated from Yamame and Amago, which live in the same streams.

What does White spotted Char (Iwana) sushi taste like?

Because Iwana is in the salmon family, they descend to the sea or lakes during their growth period and migrate up rivers as adults. Most of the rivers in Japan are among the world’s steepest, with short lengths, elevation differences, and fast currents. Therefore, it is thought that Iwana has the strength and muscles to withstand the rapid river currents and become tighter. The best ways to cook tight-fleshed Iwana are deep-fried, grilled, and sashimi, which takes advantage of the fish’s firmness when eaten. Arctic char, a close relative, is highly prized in French cuisine, and lives in Lake Leman and Lake Annecy, and is actively farmed in many areas.

Even Iwana pressed sushi is quite rare, but if you want to eat nigiri sushi, you will have to go to a restaurant adjacent to an aquaculture farm in Nagano or Toyama. It may look like Shiromi, but it has the flavor of salmon itself. However, the meat and flavor are somewhat inferior to those of Yamame and Amago.

If you really want to try Iwana nigiri, you can find it at the Gokayama ShunsaiKobo Iwana in Toyama Prefecture.

Address: 72-1 Nishiakao-machi, Nanto City, Toyama Prefecture (in the Sasara Building)

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Revision date: March 14, 2025

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What is Sakhalin taimen (Itou)?

Sakhalin taimen is distributed only in the southern Kuril Islands, Sakhalin, Primorsky Territory, and Hokkaido. It used to be distributed in Lake Ogawara, Aomori Prefecture, but has already become extinct. In Hokkaido, it inhabits gently meandering rivers in the Konsen Plain, Sarufutsu Plain, and Sarobetsu Plain.

Reaching a maximum height of 2 m, it is the largest freshwater fish distributed in Japan. Its Japanese name is Itou and its scientific name is Parahucho perryi  (Brevoort, 1856).

The body color is light purple or light green on the back side and silvery white on the belly side. Unlike other salmonids, Sakhalin taimen lay their eggs in the spring and do not die, but instead lay them over and over again for many years. Females are usually larger than males, sometimes twice as large as males. The “魚鬼” Chinese character combines “魚” (fish) and “鬼” (devil). As the Chinese characters suggest, it is known for its ferocious nature.

It is also farmed in Aomori and Niigata, but because it takes 5~6 years to grow to 50 cm in length, it is not commercially available and is used at hotels and other places as a regional specialty.

What does Sakhalin taimen (Itou) sushi taste like?

Its flesh is not peculiar and is a slightly pale orange color. The texture is tender but strangely does not feel tender and melting. It is rarely served at sushi restaurants in Tokyo, but it is probably farm-raised Sakhalin taimen. Whether or not it is a natural product, it is a very rare topping, so if you find it, you should definitely try it.

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What is Brown trout?

In Europe, the word “Trout” often refers to Brown trout. It has been transplanted to many parts of the world as an angling target fish.

Since the 1860s, it has been transplanted to all parts of the world and has become established in natural waters. It appears to have been transplanted to Japan in the 1930s via the U.S. mixed with Brook trout eggs, and natural reproduction has been confirmed in Lake Chuzenji, Lake Ashi, and the upper reaches of the Katsura River.

Body shape is similar to Rainbow trout, etc. The body color is grayish blue with relatively large black spots on the dorsal surface of the body and near the base of the dorsal fin, and whitish-orange spots below the lateral line. 1-5 years in freshwater, then become smolt and descend to the sea, spending 6 months to 5 years in the ocean. The descending type is also called Seatrout. Some spend their entire lives in freshwater areas such as rivers and lakes. It reaches a maximum length of 0.7 m.

What does Brown trout sushi taste like?

Brown trout is said to have less fat and a lighter flavor than rainbow trout, and when eaten as sashimi, it should be frozen completely before eating, since it is a freshwater fish, it is possible that parasites may be hidden in it. It also has a fishy odor unique to river fish, so it is necessary to quickly remove the blood. However, we have never heard of a sushi restaurant serving brown trout nigiri. Brown trout and Rainbow trout hybrids are sold as Shinshu-salmon (信州サーモン), and their market price is over 2,000 yen per kilogram. Shinshu-salmon nigiri is commonly eaten in Nagano and other places in Japan.

In Europe, where it originated, it is a high-grade fish that is delicious to eat. It is farmed mainly in France and Austria for eating purposes. However, compared to Rainbow trout, it grows more slowly and is more difficult to farm, so there are only a few companies that provide it. Hence, it is expensive. The main way to eat trout is to cook it. Incidentally, Schubert’s song “The Trout” was inspired by the brown trout.

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Toro was originally used for bluefin tuna (and later for all tuna), but Beni toro was probably the first example of the term being applied to a fish other than tuna.

Around 1970, a major fishery company called Kyokuyo (極洋) gave the name to a sashimi product of fatty Benizake (sockeye salmon; Oncorhynchus nerka) caught in the North Sea, which had not yet entered the spawning migration stage.

It took many years from application to approval due to various problems, but Beni toro became a legitimately registered trademark in 1987. The registration number is 1991889.

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What is Biwa trout (salmon)?

Biwa trout is a species of fish native to Lake Biwa, but is also found in Lake Kizaki, Lake Chuzenji, Lake Ashi, and other lakes through transplantation. The Japanese name for Biwa trout is Biwa masu (琵琶鱒). As indicated by its scientific name, Oncorhynchus masou subsp., it is considered to be a subspecies of Satsukimasu (Red-spotted masu trout). It reaches up to 60 cm, and the spots on the body are pale orange and disappear with growth. The adult one has a silver colored body.

It has also been farmed in Japan for a long time. There is even a famous Biwa trout farm near Lake Biwa in Shiga Prefecture that has been in operation since 1878.

An interesting fact about Biwa trout is that it is a landlocked variety of Pacific Salmon while being anadromous as it moves between the freshwater lake Biwa and surrounding rivers according to the water temperature as part of its life cycle.

What does Biwa trout sushi taste like?

The natural Biwa trout season is from June to early September. At this time of year, it has no peculiar flavor and has large amounts of fat with refined sweetness. When you put it in your mouth, only the delicious flavor of the fat spreads out as if it were melting softly. The rich flavor of trout can also be fully enjoyed as a sushi topping.

Sushi restaurants in Shiga prefecture, such as Kyogoku-zushi, serve Biwa masu nigiri sushi during the summer months. Ordinary Ikura is red in color because salmon go down to the sea and feed on crabs and shrimps, taking in red pigment. Biwa masu, on the other hand, grows only in lakes, so it does not take in any pigment and its eggs remain golden. Kyogoku-zushi also offers this Golden Ikura sushi. Both are rarely seen at sushi restaurants in Tokyo.

On June 21, 2025, an international academic journal published a new scientific name, “Oncorhynchus biwaensis,” for this salmon species, which is endemic to Lake Biwa.

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In the same way, there is no fish called “toro salmon”. Just like tuna, “toro” refers to the fatty part on the belly side of the salmon. It is also called “harasu” in Japanese. This is how the word is used at some scrupulous sushi restaurants. This description of “toro salmon” is correct.

Most salmon used at conveyor belt sushi restaurants is either trout salmon or Atlantic salmon. The reason this salmon can be served at the cheap price of US $1 or $2 per plate (2 pieces of sushi) is that these particular fish are all farmed and are available in bulk quantities from overseas. This salmon is mainly imported to Japan from Norway, Chile, Scotland and Canada.

Actually, the popular “toro salmon” topping is made from these imported items and the fat content is three times that of wild salmon. Feeding farmed salmon plenty of solid compounded feed that is high in protein and high in fat, turns the entire body to toro.

Salmon, which are born in freshwater and migrate downstream to the sea are called “sea-run fish” and they may be farmed in either seawater or freshwater. Trout salmon is “former” rainbow trout that was raised in a fish cage in the sea. In the wild, the sea-run rainbow trout grows up to 1 m in length, its body turns silver and the meat takes on a red color. The wild version of these are called “steelhead” and fetch a high market price, so they are not used in conveyor belt sushi restaurants.

Just like other aquaculture, salmon farming faces some difficult issues. It may surprise you that salmon is actually a white fish, originally. In the wild, the salmon meat gets a red color from feeding on crustaceans such as crab and shrimp that contain the red pigment astaxanthin. However, in the fish cages where the salmon are surrounded by nets, the food chain is also restricted. The compound feed would be plenty if the goal was only to raise bigger fish, but that results in a grey color or light yellow meat that doesn’t even resemble the salmon pink (orange?) that everyone wants and they don’t sell.

Therefore, when making the solid compounded feed, artificial coloring is mixed in. One of the colorings is called canthaxanthin. This is a synthetic chemical derived from petroleum. There is a color chart with 10 different, detailed levels of red coloring and buyers can even indicate which color they would like and the farmers can achieve it. It’s kind of like an industrial product that is being manufactured. Japanese people prefer a dark red color for salmon in the same way they do for tuna, so the coloring for Japan’s market is adapted to that.

When light is shone on wild salmon, the red coloring looks faded, but the light makes farmed salmon that have been fed coloring, look brighter. Artificial coloring is a necessity in farmed salmon and this is true for the trout salmon and Atlantic salmon that are used as the ingredients for toro salmon as well. All of the farmed salmon in circulation have been colored in this way, so much so that it wouldn’t be surprising if the insides of their stomachs were stained red. The flamingos at zoos also get their beautiful pink feathers from these chemicals.

Trout salmon is rainbow trout that has been farmed in the sea. On the other hand, rainbow trout farmed in freshwater is called Donaldson trout. Of all the large rainbow trout gathered at each location, those with small heads and fat bodies were selected and bred over many years to create this type. The objective of choosing a small head is to make more meat. They are characterized by their fast growth and while normal, farmed rainbow trout grow to about 30 to 40 cm, Donaldson trout grow up to nearly 1 m. The name is taken from the American who developed this variant.

The Donaldson trout is farmed throughout Japan and is used as toro salmon and aburi salmon at conveyor belt sushi restaurants. Since they are supplied directly to the processor (of the salmon) from the farmer without going through the market, they may be sold cheaper than the import price. Just like the imported salmon, this farmed salmon is also fed artificial coloring. There are also already new variants improved from the Donaldson trout being bred. Trout made from breeding Donaldson trout females and steelhead males are called Donaldson steelhead, for instance. They grow even faster.

Ample use of the latest biotechnology has been made in salmon farming and some of these technologies include creating young fish without functioning reproductive organs, “triploids” which means increasing the size of the fish up to triple and “all female populations” where males are converted into females. The triploid fish grow large in correlation to the lack of energy exertion. The objective of all-female populations is to get more masuko (ovaries). Masuko is used for the ikura (salmon roe) at conveyor belt sushi, and since the fish that the roe is harvested from have an inferior flavor, they are used for aburi salmon. Now, there are even triploid, all-female farm populations. No wonder the restaurants can serve a plate (2 pieces) of salmon sushi for US $1.

The simple phrase, “toro salmon” contains so much meaning.

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Related contents:

What is Beni toro?

What is Biwa trout?

What is Brown trout?

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Revision date: February 16, 2023

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