What Is Sashimi- or Sushi-Grade Fish? A Detailed Guide

The terms "sushi quality" and "sashimi quality" are commonly used to describe fish or seafood deemed suitable for raw consumption. While the designation may sound authoritative, it is not a legally defined quality standard by current regulatory measures. It is rather a generally accepted trade and marketing term, used to assist customers in selecting certain ingredients or to promote the sale of specific fishery products.

Consequently, many commercially available fish and seafood are suitable for preparing sushi or sashimi, provided they meet certain quality and safety criteria. Many countries have established specific guidelines and standards in this regard. These regulate how fish and seafood must be handled when intended for raw consumption. In particular, such regulations typically address requirements for maintaining the necessary cold chain, hygiene, and the targeted elimination of parasites potentially harmful to humans. The preparation of sushi or sashimi is only one of many possible raw dishes. The corresponding regulations therefore focus on food safety and are less concerned with qualitative (organoleptic) characteristics such as taste, appearance, odor, and color. Nevertheless, precisely these characteristics – alongside freshness and safety – play a central role in selecting ingredients for sushi and sashimi.

Consumers encounter the designation at fishmonger counters, in supermarkets, or in various online shops. It generally describes suitability in the sense of food law rather than "quality" in the specific sense. The range of suitable and "safe" ingredients therefore spans from inexpensive commodity products to high-priced premium goods.

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The quality of raw ingredients substantially determines the sensory outcome when preparing sushi and sashimi. An exception applies to fish that have already undergone aging to enhance flavor. During the aging process, objective quality characteristics deteriorate, yet flavor intensifies.

Whether fatty fish such as salmon or lean fish such as sea bass – the higher the quality of the raw ingredient, the more pronounced the sensory result. Origin and seasonality play a significant role, particularly for wild-caught species. Climatic influences and spawning timing affect physiology as well as fat content and, by extension, flavor.^2, 3 Purchase price is not necessarily an indicator of quality or flavor, though both regularly correlate with a higher price. For farmed fish, products from high-quality aquaculture operations are frequently superior in flavor to those from conventional aquaculture – especially when low stocking density, gentle husbandry, suitable feed, and specialized slaughter methods (e.g. ikejime (活け締め, brain-spiking method)) are employed.

Most wild-caught species available through mainstream trade originate predominantly from commercial or industrial fisheries. Possible catching methods range from rod and line to kilometer-long trawl nets. In principle, any catching method can be used to supply fish of sushi or sashimi quality. On the other hand, the catching method can be responsible for the difference between premium and standard quality.⁴ The more sought-after a species, the more likely that catching methods are differentiated with regard to quality, as in the case of tuna.

Nunawwoofy. Fresh fish on ice at the fish market . All rights reserved ©

Freshness of fish and seafood is a central quality criterion for preparing sushi and sashimi.⁵ In a food context, "freshness" denotes the state of an ingredient in which its original properties are largely preserved. Fish and seafood are extraordinarily perishable compared to other foods. After death, proteins and fats are broken down by enzymes, leading to changes in texture and flavor. At the same time, bacterial growth accelerates, which can pose health risks when consumed raw.

To preserve freshness, fish intended for sushi or sashimi is rapidly chilled immediately after catch and subsequently stored at controlled temperatures just above freezing point. This slows bacterial growth without forming ice crystals that could damage the delicate flesh. Spoilage thus serves as an indicator of undesirable changes following catch or slaughter and directly affects the quality and safety of the final product. For certain species – particularly tuna (maguro, 鮪), Japanese flounder (hirame, 鮃), and mackerel (saba, 鯖) – controlled aging can be employed to improve flavor and texture.⁶ This process is carefully monitored and always begins with fresh fish. Through aging, certain compounds are broken down, resulting in a more complex flavor profile and a more tender texture – but requires expertise to prevent spoilage. Even for ingredients that undergo an aging period, the initial freshness determines flavor development and the safety of the final product.

Assessing and maintaining freshness are core competencies in the preparation of sushi and sashimi. This encompasses proper storage and handling as well as sensory evaluation based on odor, color, and firmness.

The preparation of sushi and sashimi places particular demands on food safety and hygiene. Since raw fish and seafood are consumed without germicidal heating, freshness, preservation, hygiene, and the management of parasites are the central factors of risk control.

SUSHIPEDIA. Influence of storage temperature on the quality of striped tilapia. All rights reserved ©

From a microbiological-hygienic perspective, raw fish and seafood rank among the particularly sensitive foods. The spoilage process is triggered by the action of enzymes, bacteria, and chemical reactions. The longer the time since death, the more advanced the growth of potential pathogens. When using raw ingredients, a certain baseline microbial load should generally be assumed. Through processing and preparation, this microbial load expectedly increases further. This underscores the importance of freshness and the quality of the starting product, as sushi or sashimi is usually consumed raw, without prior germicidal heating.

The spoilage process is generally accompanied by changes in the physical properties of the raw material. These changes lead to a deterioration in food quality – color, texture, and flavor. Even chilling or freezing cannot fully halt this quality loss, only slow it.⁷

Non-disclosed author. Octopus in ice in plastic box. All rights reserved ©

In everyday language, "freshness" occasionally serves as a synonym for catch-freshness. This is typically interpreted as meaning that the product has neither been frozen nor is currently frozen. However, freezing fish or seafood does not diminish freshness but rather serves to preserve it. It must be noted, though, that while freezing extends the shelf life of food, it also inevitably leads to some impairment of food quality.⁷ The degree of quality loss is substantially determined by the freezing technology used.

Professionally and industrially frozen fish and seafood have the advantage over catch-fresh products of considerably longer storage life. Freezing is one of the most effective forms of food preservation. Parasites are killed at sufficiently low temperatures, and bacterial growth is largely inhibited at temperatures from –18 °C – although many bacterial species can survive freezing. The use of industrial flash-freezing reduces the deterioration of food quality to a minimum.⁸ Fish or seafood that have been preserved by flash-freezing immediately after catch therefore represent adequate and qualitatively satisfactory ingredients for sushi or sashimi preparation.

SUSHIPEDIA. Preference for sushi made from frozen and non-frozen ingredients. All rights reserved ©

Deep-frozen foods often have a reputation for being inferior to fresh products. From an organoleptic perspective, the fresh product that has been appropriately chilled and consumed promptly holds the advantage. Freezing – particularly slow freezing – can negatively alter the textural properties of products. With flash-freezing, however, these properties are better preserved, and the differences from a fresh product are very slight to partially imperceptible. The extremely short freezing process during flash-freezing causes the cellular fluid to form only very small ice crystals, so that cell structures remain intact. The degree of cellular damage is directly related to food quality in terms of flavor, texture, nutritional value, and appearance.⁹ Modern methods make it possible to preserve fish and seafood without substantially diminishing their sensory properties or nutritional value.

Strict hygiene measures during the preparation of sushi and sashimi are fundamental to the safety and quality of the dishes.¹⁰ The process begins with the careful selection of fresh, high-quality ingredients, with particular attention to the freshness and origin of fish and seafood. Maintaining an unbroken cold chain from procurement through processing is essential to prevent bacterial proliferation. Before preparation and continuously throughout, work surfaces, utensils, and hands must be thoroughly cleaned to minimize the risk of cross-contamination. Although the use of disposable gloves can be advantageous, it does not replace the need to wash hands regularly. The preparation of nigiri sushi (握り寿司) in particular proves ineffective with gloves, as the fine manipulation and pressure required for shaping demand direct contact. Moreover, touching kitchen areas with soiled gloves can result in even more severe germ transfer. Changing gloves at every instance of soiling is also resource-intensive, while their reuse can lead to even more unhygienic conditions.

Proper storage of ingredients at appropriate temperatures is essential to prevent microbial growth and toxin formation. Separate storage of raw fish and other foods is necessary to avoid cross-contamination.

For professional processors and restaurants, the HACCP system (Hazard Analysis and Critical Control Points) provides the framework for systematic risk analysis. The seven basic principles of the HACCP system allow critical control points – from ingredient procurement through preparation and presentation – to be identified and monitored. This includes measures such as temperature control of raw ingredients and ensuring the aforementioned hygiene practices. Regular staff training in the correct handling and processing of food, as well as updating HACCP plans to reflect new procedures, are also part of this framework.

SUSHIPEDIA. Parasite in the flesh of fish for sushi. All rights reserved ©

When consuming fresh, previously unfrozen fish or seafood raw, there is a risk that they may harbor viable parasites harmful to humans.¹¹ Fish and seafood caught in the wild are particularly difficult to assess regarding potential parasite infection.

These parasites represent a significant challenge in the safety and quality of seafood, particularly in the preparation of sushi and sashimi. Among the various parasites that can occur in fish and seafood, Anisakis simplex is one of the most relevant and concerning. A. simplex is a nematode parasite found in certain fish species that can cause anisakiasis in humans who consume infected raw or insufficiently cooked fish. This parasitic infection can lead to symptoms such as nausea, vomiting, and abdominal pain. Preventing parasite infection requires careful preventive measures, including the selection of fish from safe sources, appropriate processing, and specific procedures to kill any parasites before the fish is prepared for consumption.

Particularly with regard to raw consumption, it must be ensured that no viable parasites are present in foods intended for raw consumption. Detecting parasite infestation – for example by candling filleted fish – is only partially effective. This method captures only parasites lying immediately beneath the surface and can therefore only provide information about a fraction of the total load.¹² Epidemiological data from the origin fishing grounds can provide insight into the risk of possible parasite infestation but are no absolute guarantee for the absence of parasites in wild-caught fish.^13, 14 To kill nematodes in fish intended for raw consumption, the two principal regulatory frameworks prescribe the following freezing conditions:

Both the FDA and EU regulations operate within the Codex Alimentarius framework for food safety (CAC/RCP 52-2003), which identifies freezing as a control measure against parasites in fishery products but does not prescribe specific temperatures or holding times. The identical temperature thresholds in both systems reflect a shared scientific basis rather than a common regulatory source.

Canadian provincial food services codes prescribe the same conditions as the FDA. The UK applies the EU requirements as retained law post-Brexit.¹⁶ Australia and New Zealand have no prescriptive time-temperature requirements for parasite destruction; FSANZ recommends freezing for at least 7 days without specifying a temperature, and parasite control is managed through HACCP-based food safety programs at the business level.¹⁷ Japan's MHLW recommends –20 °C for at least 24 hours, though this is advisory rather than legally binding.¹⁸

Most domestic household appliances are incapable of maintaining a continuous temperature of at least –20 °C. Furthermore, the study by Podolska et al. (2019) demonstrates that the speed of the freezing process warrants consideration and that extended storage times should be taken into account accordingly.¹⁹ The study by Sanchez-Alonso et al. (2018) suggests that domestic freezers operating at low cooling capacity and with uneven temperature distribution may not reliably ensure the complete inactivation of Anisakis larvae.²⁰ This poses a potential health risk.

Non-disclosed author. Aquaculture in Mediterranean sea. All rights reserved ©

When fish or seafood originate from aquaculture, the freezing treatment otherwise mandatory for raw consumption under the EU regulation may be waived under certain conditions. For safe consumption, the following conditions must generally be met according to this EU regulation:¹⁶

• Animals reared exclusively from embryos
• Feed in which no viable parasites are present
• Rearing of animals in an environment epidemiologically demonstrated to be free of parasites. (However, if the farming operation employs officially approved procedures that ensure no viable parasites are present in the products and thus pose no health risk, this requirement may be waived.)

Farmed fish and seafood reared in land-based tanks or closed recirculating systems and fed with suitable feed are considered relatively safe regarding the presence of parasites that pose a health risk. The prerequisite, however, is that the farmed animals were raised from embryos rather than taken from the wild, and that the water supply is demonstrably free of parasites.

The U.S. Food and Drug Administration (FDA) maintains a list of species whose risk of infestation with parasites harmful to humans is rated as high, but also recommends an individual assessment of the situation regarding raw consumption even for species classified as low-risk.¹⁵ The European Commission states that the parasiticidal freezing treatment of wild catches may be waived when epidemiological data indicate that the origin fishing grounds pose no health risk regarding the presence of parasites and the competent authority has granted approval.¹⁶ The European Food Safety Authority (EFSA), however, concludes that based on current knowledge, no marine fishing grounds can be considered free of Anisakis larvae.²¹

For farmed Atlantic salmon (Salmo salar) reared in floating cages (marine aquaculture), the probability of parasite infection is assessed as low by the European Food Safety Authority (EFSA). Apart from Atlantic salmon, insufficient monitoring data exist for other species from aquaculture. It is therefore not possible to identify further fish or seafood species from marine aquaculture that pose no health risk regarding the presence of parasites.^14, 22

In international comparison, Japan is characterized by a less restrictive regulatory approach to raw fish consumption. While legally binding regulations in the USA and Europe stipulate under which conditions fish must be frozen for raw consumption in order to eliminate parasites such as A. simplex, no corresponding statutory freezing requirement exists in Japan. The Japanese Ministry of Health, Labour and Welfare (MHLW) issues recommendations that suggest freezing at –20 °C for at least 24 hours – these are, however, not legally binding.¹⁸ Japan instead relies on a combination of official recommendations, the expertise of those preparing the food, and administrative sanctions in the event of harm.

The Japanese Ministry of Agriculture, Forestry and Fisheries provides detailed recommendations for handling fish intended for raw consumption. These recommendations include that freshly purchased fish should be adequately chilled, transported, and gutted without delay. The need to remove the internal organs promptly stems from the fact that Anisakis larvae primarily parasitize the surface of the organs. As freshness declines and time progresses, these parasites can migrate into the musculature – the edible portions of the fish. It is further recommended to consume fresh seafood that has been sufficiently frozen (at least 24 hours at –20 °C or 48 hours at –18 °C). For business operators, the Japanese Ministry of Health, Labour and Welfare provides clear instructions: fish should be as fresh as possible and gutted immediately. The consumption of raw fish viscera should be avoided. Visual inspection and removal of Anisakis larvae is essential and recommended, as is freezing the fish (at least 24 hours at –20 °C) or heating (1 minute at 70 °C or higher).

The Japan Fisheries Association emphasizes that the only method for completely preventing anisakiasis is freezing or heating the fish. There is, however, a discussion among professionals who maintain that careful inspection of each individual fish can prevent anisakiasis.²³ This view reflects the high value that Japanese gastronomy places on the freshness and quality of sushi and sashimi. Critics argue that an inspection-based approach depends heavily on the individual skills of chefs and can lead to inconsistent safety standards.²⁴

The practical prevention of anisakiasis in Japanese gastronomy follows a multi-stage methodology documented by the Japan Fisheries Association (JFA) in a practice-oriented guidance document for professionals.²³ The document captures the prevailing attitude of many chefs and fish dealers in a characteristic quotation:

The guidance document juxtaposes this self-understanding with a differentiated cascade of methods that extends well beyond mere visual inspection. At its center stands the principle that the decision on the method of preparation is made during filleting – not at the point of purchase. A fish that was intended for sashimi can be redirected during butchering to soup, braised dish, or tempura if a high parasite load becomes apparent. This flexibility – formulated in the document as "not insisting on sashimi" (刺身に執着しない, sashimi ni shūchaku shinai) – is regarded as a fundamental working principle.²³

The methodology begins before processing. Professional chefs typically maintain close relationships with their market suppliers and obtain up-to-date information about the parasite load of specific fishing grounds and species. Indications that mackerel from a particular region is currently heavily infested, for example, circulate through the Japanese fish markets and feed directly into purchasing decisions.²³ Upon delivery, the viscera are removed without delay while the fish is still consistently chilled to below 6 °C. At these temperatures, Anisakis larvae are largely immobile and remain predominantly on the surface of the organs. The number of visible larvae on the viscera is recorded during gutting and serves as the basis for deciding the further use of the fish: with a high infestation, the fish is not served raw.²³

During subsequent filleting and portioning, further control techniques may be employed. The guidance describes holding fillets against light to make embedded larvae visible. Thin slicing – under one centimeter – increases the likelihood of discovering or mechanically damaging hidden parasites. In this context, the traditional technique of ika sōmen (イカそうめん) – squid cut into very thin strips – is interpreted as a traditional form of parasite control.²³ Increasingly, UV light (blacklight, approximately 370 nm wavelength) is used as a supplementary tool: Anisakis larvae fluoresce blue-white under UV irradiation, facilitating detection at the surface. This method has become widespread particularly in supermarkets and at fish counters though some restaurants have adopted it as well. Larvae embedded deeper in muscle tissue remain invisible, and not all Anisakis species fluoresce equally.²³

The JFA explicitly categorizes this practice as a cultural technique: the ability to safely prepare fish raw is a distinct craft skill (gijutsu, 技術) whose transmission is as significant as food safety itself. The document cautions against creating an "entirely frozen raw fish culture" (全て冷凍の生食文化, subete reitō no seisei bunka) through a general freezing mandate – arguing that the majority of wild-caught species used for sushi and sashimi cannot be farmed, and a freezing requirement would make fresh raw fish consumption impossible for many species.²³

A structural side effect of this inspection-based approach concerns the relationship between restaurant types. High-end sushi restaurants preferentially use fresh, never-frozen wild fish – raw material in which viable parasites have not been excluded through freezing treatment. The Anisakis risk there is theoretically structurally higher than at kaiten sushi (回転寿司, conveyor-belt sushi) chains, which predominantly work with industrially flash-frozen products.

Since 2013, Anisakis has been recorded as a separate cause in the MHLW's Japanese food poisoning statistics. Since 2018, Anisakis has consistently ranked first among all causes of reported food poisoning – in some years, nearly half of all registered incidents were attributed to this parasite.²⁵ The reported case numbers have fluctuated considerably in recent years: 566 cases in 2022, 432 in 2023, and 330 in 2024.²⁵ A characteristic feature of anisakiasis is that virtually every incident involves a single patient – group outbreaks are rare.²⁶

In 2018, the number of Anisakis cases rose sharply. A special study by the MHLW identified bonito (katsuo, 鰹) as the primary cause: unusually high water temperatures had shifted the fishing grounds and exceptionally increased the parasite load in katsuo that year.¹⁸ This incident illustrates the influence of climatic fluctuations on the parasite load in wild fish – a factor that eludes purely inspection-based prevention.

The absence of a freezing mandate does not mean the absence of consequences. If a foodservice establishment causes an Anisakis food poisoning incident, it faces an administrative business closure order (eigyō teishi shobun, 営業停止処分), whose duration varies by prefecture. In 2018, the MHLW requested the responsible prefectural authorities to limit the closure period to the time necessary for staff training and recurrence prevention, and to restrict the scope to fresh fish products.¹⁸ The Japanese approach thus combines methodological freedom in prevention with liability in the event of harm.

In January 2025, the Japanese Food Safety Commission (Shokuhin Anzen Iinkai, 食品安全委員会) published a comprehensive risk profile on Anisakis.²⁶ Among its findings, the report states that a single larva is sufficient to trigger anisakiasis and that the contamination rate for the same species fluctuates considerably from year to year – depending on water temperature, fishing ground, and ecological conditions. At the same time, the risk profile notes that for fish from complete aquaculture (kanzen yōshoku, 完全養殖) – in which the entire life cycle from egg to slaughter is controlled – elimination of Anisakis is possible, provided feed and water supply are free of viable parasites.

Japan's approach to raw fish consumption is based on a combination of governmental recommendations, expertise, and practical skills of those preparing the food. While the USA and Europe give preference to strict regulations, Japan emphasizes the importance of training and experience in handling raw fish. Among trained and professionally educated chefs, the risk of infection is low, as their training includes the identification and removal of parasites. A residual risk, however, cannot be entirely excluded.

Not all fish species are used untreated for preparing sushi or sashimi. Mackerel, Pacific herring, or young sea bream, for example, are marinated in an acidic solution of salt, vinegar, soy sauce, or other ingredients. A widely used Japanese method is sujime (酢締め, vinegar curing): raw fish is coated with salt, rinsed, and soaked in vinegar. Through osmotic pressure, the salt initially draws water from the surface of the fish and firms the muscle protein. Subsequently, the vinegar also acts on the protein, hardening it while small bones become softer. Through this process, the fish becomes firmer, takes on the flavor of salt and vinegar, and retains moisture. A popular sushi or sashimi ingredient prepared by this method is shime saba (しめ鯖). While marinating produces a certain antibacterial effect, it has only a marginal influence on potentially present parasites. Although some culinary or sushi literature may encourage killing parasites through marinating,²⁷ studies demonstrate that traditional marinades are ineffective and therefore do not represent an adequate alternative to freezing treatment.²⁸ An exception is the traditional German or Danish method of marinating herring fillets. This method, however, requires a storage period of at least 5 to 6 weeks in an 8–9% salt solution to ensure that all parasites are killed.²⁹ To reliably kill parasites using a salt and vinegar solution within a short period, the pH value would need to be so low as to render the flesh nearly inedible.

Non-disclosed author. Classic Japanese sushi with raw tuna on a white plate on a gray table. Japanese cuisine. Close up, selective focus. All rights reserved ©

Fish and seafood for sushi or sashimi must be fresh and comply with applicable food safety regulations. Wild-caught marine and freshwater organisms may contain viable parasites that endanger human health. Candling and visual inspection during filleting are common methods for detecting parasite infestation but are less reliable for large species or unprocessed fish and seafood. Wild catches without proper freezing treatment therefore carry an elevated risk as raw ingredients for sushi or sashimi. Farmed fish and seafood can be processed catch-fresh under the conditions described above. When non-flash-frozen wild fish is used, thorough parasite control by experienced professionals is required – with a slightly elevated residual risk compared to flash-frozen products.

Beyond safety, the freshness and quality of ingredients determine the sensory outcome. Catching methods, farming conditions, prompt chilling, and proper storage are the principal influencing factors.