Quick summary
Anisakis is a major commercial risk in wild-caught fish, affecting food safety, border compliance, and marketability. Larvae may migrate from viscera to muscle, especially if chilling and freezing are delayed. Freezing or heat kills them, but does not remove visible worms or all allergens. EU controls focus on visible parasites in edible flesh, which can lead to rejection or downgrading of imports. Risk is reduced by careful sourcing, rapid chilling, evisceration, trimming, and full traceability.
Introduction
Anisakis spp. are marine nematodes whose adult stages live in marine mammals; crustaceans act as intermediate hosts, fish and cephalopods as paratenic hosts, and humans are accidental dead-end hosts after eating raw or insufficiently processed seafood. In commercial control work, anisakis matters commercially because it sits at the ugly intersection of public health, consumer acceptance, official controls and border compliance. EFSA’s 2024 re-evaluation concluded with 99% to 100% certainty that no particular wild-caught fish species from any marine fishing area consumed in the EU/EFTA can be regarded as free of zoonotic parasites of public-health importance, and reaffirmed the earlier conclusion that no sea fishing grounds can be considered free of Anisakis simplex larvae.
Although anisakis simplex is found in many commercial fish species, including hake, blue whiting, mackerel, herring and cod. The scientific question is not whether these species can carry anisakids. They surely can. The practical questions are how often, where in the fish, how dangerous they are to people, and what happens when veterinary inspectors or food operators find them.
Health effects in fish and humans
In fish, Anisakis simplex larvae usually lodge in the viscera, body cavity, liver, or muscle and trigger local tissue reactions such as inflammation, encapsulation, granuloma-like lesions, and other histopathological damage. In heavily infected fish, this can impair tissue quality and reduce the commercial value of the fillet, even when the fish does not show dramatic signs of disease. In practice, the biggest impact is often on marketability of the flesh rather than obvious clinical illness in the fish. Once the fish is caught, Anisakis simplex tries to make its way out of the body and this often results in more worms present in muscle tissues of a late frozen fish.
In humans, Anisakis behaves as a classic foodborne zoonotic parasite and is acquired mainly by eating raw or undercooked infected marine fish. The larvae do not develop into adult worms in people, but they can invade the gastrointestinal wall and may cause symptoms such as acute abdominal pain, nausea, vomiting, and diarrhea. It is also important to notice that anisakis can cause allergic reactions ranging from urticaria and angioedema to severe anaphylaxis, and sensitised people may react even to parasite material from dead larvae, because some allergens still remain active after processing.
Currently, the general practice of killing the parasites of Anisakidae family is quite simple – first, via freezing treatment, which should lower the temperature in all part of the product to either -20 °C or lower for not less than 24 hours, or to -35 °C or lower for not less than 15 hours. Second, and more consumer oriented (in case the product is bought fresh and has never been frozen) the legislation specifies a heat treatment with a core temperature of 60° C or more for 1 minute. Reaching such a core temperature depends on the thickness and composition of the product. It has been estimated that a 3 cm thick fillet should be heated for 10 minutes to ensure that Anisakis spp. larvae are destroyed.
Why anisakis leads to rejection and downgrading of the fish
RASFF (Rapid Alert System for Food and Feed) data from 2001 to 2025 show that Anisakis accounted for 73.6% of all parasitic infestation notifications, of which more than 27% were border rejections and more than 22% were alerts. Fish and fish products made up almost 97% of these notifications, with mackerel, hake, herring, cod, and anchovies together accounting for more than 75%.
Given that virtually all wild-caught fish may contain Anisakis, frozen fish imports can become a very expensive lottery, as border inspection may reject the goods or downgrade them. It is therefore absolutely vital to understand the legislation and procedures in order to minimize the commercial impact of rejected or downgraded import cargoes.
Under EU hygiene law, food business operators must visually examine fishery products for visible parasites before placing them on the market and must not place fishery products that are obviously contaminated with parasites on the market for human consumption.
Official controls on fishery products specifically include parasite checks, and competent authorities must declare fishery products unfit for human consumption when the relevant parasite requirements are not met. Methods used for parasite detection usually include visual inspection and candling, as these are fast and non-destructive allowing parasites to be detected with a high degree of probability.
In commercial terms, this means following: the key legal test is the visibility of parasites in the edible meat, not merely the existence of a parasite somewhere in the fish. If the edible parts are visibly contaminated, the operator must keep the product off the market. In veterinary border control practice, this is exactly why Anisakis often becomes a reason for rejection. In many countries, the phrase “must be kept off the market” practically means that sound fish may still be rejected for import and must either be physically destroyed, returned to the country of origin, where it will most likely also be destroyed, or downgraded in order to protect the human consumption segment.
Downgrading into CAT2 or CAT3
We need to clearly differentiate the possible downgrade categories, namely CAT 3 and CAT 2. Under EU animal by-products law, Category 2 is the intermediate-risk group, while Category 3 is the low-risk group. For fish products, the practical distinction is this: Category 3 usually covers fish or fish by-products from animals that did not show signs of disease communicable to humans or animals and that are simply no longer intended for the human food chain, whereas Category 2 usually covers fish products that are non-compliant, contaminated, or otherwise higher-risk.
Under the same EU law, aquatic animals and parts from establishments producing products for human consumption, as well as products no longer intended for human consumption for commercial or other defect-related reasons, can fall under Category 3. That is why fish or trimmed portions removed from the food chain after parasite findings are often handled operationally as Category 3 material.
However, a third-country consignment that fails to comply with EU import rules at the border is treated differently. Regulation (EC) No 1069/2009 classifies imported products of animal origin that fail to comply with import requirements as Category 2 material, unless they are returned or another lawful measure is applied. Therefore, a lot of fish withdrawn from the market within the EU often ends up as CAT 3, while a non-compliant import consignment stopped at the BCP may instead be classified as CAT 2.
Having described the EU framework above, it should also be mentioned that the same practice has been implemented in many countries that apply zero tolerance for Anisakis in edible parts of the flesh. These include two major importers of groundfish and pelagic species, Moldova and Ukraine, which have officially informed the respective health attestation bodies in exporting countries about the relevant border checks and rejection procedures.
Ways to minimise Anisakis-risk in the fish
It is, of course, impossible to “cure” a wild fish after capture, but there are several ways to reduce the parasite burden in the edible flesh and minimize the resulting commercial damage.
The first lever is sourcing and handling: choose lower-risk origins where infestation levels are less severe. Make sure the producer has chilled the fish immediately before freezing. Recent research shows that storage below 2°C can largely prevent post-mortem migration into the muscle.
The second lever is anatomical targeting. In cod, more than 85% of Anisakis larvae found in the flesh were located in the belly flaps. In North Sea herring, processing into flaps reduced overall worm occurrence 136-fold and muscle occurrence by more than six-fold. In mackerel and hake, heading and gutting remain recommended preventive measures.
The third lever is viability control. For products intended to be eaten raw or nearly raw, validated freezing or adequate heat treatment is essential and legally required. However, freezing and heating kill the larvae; they do not remove visible worms, nor do they necessarily eliminate all allergenic proteins. Therefore, a parasite-kill step is not a substitute for trimming, sorting, and visual acceptability, although it can contribute to the overall safety of products intended for human consumption.
What to do if Anisakis is found during BIP checks
The roulette was against you today, and the veterinary officer has sent you the protocol of non-compliance due to Anisakis presence. Happens in our business time to time. The operator response should be procedural, immediate and painfully disciplined. Under EU border-control rules, non-compliant consignments entering the Union are placed under official detention and refused entry, after which the competent authority orders destruction, re-dispatch to origin, or special treatment or other measures necessary to ensure compliance. The authority must hear the operator before ordering action unless immediate action is required.
At this point, there is a very clear strategy to protect the interests of importer and recover some value from the compromised lot.
1. Contact the producer and negotiate one of three variants - return of the goods, destruction of the goods or downgrade of the goods and reselling and lower price to mitigate the losses. At this moment, both importer and any trading party inbetween should be very clear that this is not their problem, and any legal action for recovery of the full amount of the cargo will be successful as it is based on non-compliance of the goods produced by the food operator with the import rules of the destination country.
2. Once consensus with the producer of the goods is found, best commercial practice would be to mitigate the loss by asking authorities to downgrade the goods into CAT3 and resell the goods for pet-food or fishmeal segments. This may result in recovery of some amount as both are not the highest paying outlets.
The key point is that all parties in the supply chain operate within the same market, and although the primary responsibility rests with the producer, they should do everything possible to help resolve the situation, including supplying the necessary documentation, arranging prompt transport solutions, and conducting effective negotiations with the authorities.
Conclusion
Anisakis simplex is not a minor cosmetic defect. In hake, blue whiting, mackerel, herring, and cod, it is a well-documented and often substantial parasitological burden, usually concentrated in the viscera but capable of reaching the edible muscle, especially the ventral portions and belly flaps. The most effective fish operator strategy is a layered one: understanding source-related and supplier-related risks, ensuring full traceability of applying immediate chilling and freezing at the source, delivering eviscerated and filleted products to highest-risk markets, and responding quickly and with clear documentation whenever the parasite is detected.
