Many species offish arecaught by humans and consumed as food in virtually all regions around the world. Fish has been an important dietary source ofprotein and othernutrients.

The English language does not have a specialculinary name for food prepared from fish like with other animals (as withpig vs.pork), or as in other languages (such as Spanishpez vs.pescado). Inculinary andfishery contexts,fish may include so-calledshellfish such asmolluscs,crustaceans, andechinoderms; more expansively,seafood covers both fish and othermarine life used as food.^[1]

Since 1961, the average annual increase in global apparent food fish consumption (3.2 percent) has outpacedpopulation growth (1.6 percent) and exceeded consumption of meat from allterrestrial animals, combined (2.8 percent) and individually (bovine, ovine, porcine, etc.), exceptpoultry (4.9 percent). Inper capita terms, food fish consumption has grown from 9.0 kg (19.8 lb) in 1961 to 20.2 kg (45 lb) in 2015, at an average rate of about 1.5 percent per year.^[2] The expansion in consumption has been driven not only by increased production, but also by a combination of many other factors, including reducedwastage, better utilization, improveddistribution channels and growingconsumer demand, linked with population growth, risingdisposable incomes andurbanization.^[2]

Europe,Japan and theUnited States of America together accounted for 47 percent of the world's total food fish consumption in 1961, but only about 20 percent in 2015. Of the global total of 149 million tonnes in 2015,Asia consumed more than two-thirds (106 million tonnes at 24.0 kg per capita).^[2]Oceania andAfrica consumed the lowest share. The shift is the result of structural changes in the sector and in particular the growing role of Asian countries in fish production, as well as a significant gap between the economic growth rates of the world's more mature fish markets and those of many increasingly important emerging markets around the world, particularly in Asia.^[2]

Over 32,000species offish have been described,^[3] making them the most diverse group of vertebrates. In addition, there are many species ofshellfish. However, only a small number of species are commonly eaten by humans.^{[citation needed]}

Fish can be prepared in a variety of ways. It can be served uncooked (raw food, e.g.,sashimi);cured bymarinating (e.g.,ceviche),pickling (e.g.,pickled herring) orsmoking (e.g.,smoked salmon); orcooked bybaking,frying (e.g.,fish and chips),grilling,poaching (e.g.,court-bouillon) orsteaming. Many of the preservation techniques used in different cultures have since become unnecessary but are still performed for their resulting taste and texture when consumed.^{[citation needed]}

The British historian William Radcliffe wrote inFishing from the Earliest Times:

"TheEmperor Domitian (Juvenal,IV.) ordered a special sitting of theSenate to deliberate and advise on a matter of such grave State importance as the best method of cooking aturbot."^[5]

Globally, fish and fish products provide an average of only about 34 calories per capita per day. However, more than as an energy source, the dietary contribution of fish is significant in terms of high-quality, easily digested animal proteins and especially in fighting micronutrient deficiencies.^[2] A portion of 150g of fish provides about 50 to 60 percent of an adult's daily protein requirement. Fish proteins are essential in the diet of some densely populated countries where the total protein intake is low, and are particularly important in diets insmall island developing States (SIDS).^[2]

Intermediate Technology Publications wrote in 1992 that "Fish provides a good source of high quality protein and contains many vitamins and minerals. It may be classed as either whitefish, oily fish, or shellfish. Whitefish, such as haddock and seer, contain very little fat (usually less than 1%) whereas oily fish, such as sardines, contain between 10–25%. The latter, as a result of its high fat content, contain a range of fat-soluble vitamins (A, D, E and K) and essential fatty acids, all of which are vital for the healthy functioning of the body."^[8]

Eatingoily fish containing long-chainomega-3 fatty acids may reduce systemicinflammation and lower the risk ofcardiovascular disease.^[9][10] Eating about 140 grams (4.9 oz) of oily fish rich in omega-3 fatty acids once per week is a recommended consumption amount.^[9][10] Increasing intake of omega-3 fatty acids may slightly reduce the risk of a fatal heart attack,^[10] but likely has little effect on the overall number of deaths from cardiovascular disease.^[11]

Fish bone is the most common food-relatedforeign body to causeairway obstruction.Choking on fish was responsible for about 4,500 reported accidents in theUnited Kingdom in 1998.^[12]

Aseafood allergy is afood allergy toallergens which can be present infish. This can result in anoverreaction of theimmune system and lead to severe physical symptoms^[13] fromurticaria toangioedema anddistributive shock. Allergic reactions can result from ingesting seafood, or by breathing in vapours from preparing or cooking seafood.^[14] The most severe allergic reaction isanaphylaxis, amedical emergency requiring immediate attention and is treated urgently withepinephrine.^[15]

Some species of fish, notably thefugupufferfish used forsushi, can result in seriousfood poisoning if not prepared properly. These fish always containtoxins as anatural defense againstpredators; it is not present due to environmental circumstances. Particularly,fugu has a lethal dose oftetrodotoxin in itsinternal organs and must be prepared by a licensedfugu chef who has passed the national examination in Japan.Ciguatera poisoning can occur from eating larger fish from warm tropical waters, such assea bass,grouper,barracuda andred snapper.^[16]Scombroid poisoning can result from eating large oily fish which have sat around for too long before being refrigerated or frozen. This includesscombroids such astuna andmackerel, but can also include non-scombroids such asmahi-mahi andamberjack.^[16] The poison is often odourless and tasteless.^[17]

Many fish eatalgae and other organisms that containbiotoxins, which are defensive substances against predators. Biotoxins accumulated in fish/shellfish includebrevetoxins,okadaic acid,saxitoxins,ciguatoxin anddomoic acid. Except for ciguatoxine, high levels of these toxins are only found in shellfish. Both domoic acid and ciguatoxine can be deadly to humans; the others will only causediarrhea,dizziness and a (temporary) feeling ofclaustrophobia.^[18][19]

Shellfish arefilter feeders and, therefore, accumulatetoxins produced by microscopicalgae, such asdinoflagellates anddiatoms, andcyanobacteria. There are four syndromes calledshellfish poisoning which can result in humans,sea mammals andseabirds from the ingestion of toxic shellfish. These are primarily associated withbivalve molluscs, such asmussels,clams,oysters andscallops.^[20] Fish likeanchovies can also concentrate toxins such as domoic acid.^[21] If suspected, medical attention should be sought.

The toxins responsible for most shellfish and fish poisonings, including ciguatera and scombroid poisoning, are heat-resistant to the point where conventional cooking methods do not eliminate them.^[17]

Fish products, especially those fromapex andhigher-orderconsumers up thefood chain, have been shown to contain varying amounts ofheavy ortoxic metals due tobiomagnification.Toxicity is a function of solubility, and insoluble compounds often exhibit negligible toxicity.Organometallic forms such asdimethyl mercury andtetraethyl lead can be extremely toxic.^[33]

According to theUS Food and Drug Administration (FDA), the risk from mercury by eating fish and shellfish is not a health concern for most people.^[41] However, certain seafood contains sufficient mercury to harm an unborn baby or young child's developing nervous system. The FDA makes three recommendations for child-bearing women and young children:

1. Do not eatshark,swordfish,king mackerel, ortilefish because they contain high levels of mercury.
2. Eat up to 12 ounces (2 average meals) a week of a variety of fish andshellfish that are lower in mercury. Four of the most commonly eaten fish that are low in mercury arecanned light tuna,salmon,pollock, andcatfish. Another commonly eaten fish,albacore ("white tuna") has more mercury than canned light tuna. So, when choosing your two meals of fish and shellfish, you may eat up to 6 ounces (one average meal) of albacore tuna per week.
3. Check local advisories about the safety of fish caught by family and friends in your local lakes, rivers, and coastal areas. If no advice is available, eat up to 6 ounces (one average meal) per week of fish you catch from local waters, but do not consume any other fish during that week.

These recommendations are also advised when feeding fish and shellfish to young children, but in smaller portions.^[41]

When the ocean conservation organizationOceana examined over 1,200 seafood samples of seafood sold in the U.S. between 2010 and 2012, they found one-third were mislabelled. The highest rate of mislabelling occurred with snapper at 87 percent, followed by tuna at 57 percent.^[42]

If fish and shellfish inhabitpolluted waters, they can accumulate other toxic chemicals, particularly fat-soluble pollutants containing chlorine or bromine,dioxins orPCBs.

Parasites in fish are a common natural occurrence. Though not a health concern in thoroughly cooked fish, parasites are a concern when consumers eat raw or lightly preserved fish such assashimi,sushi,ceviche andgravlax. The popularity of such raw fish dishes makes it important for consumers to be aware of this risk. Raw fish should be frozen to an internal temperature of −20 °C (−4 °F) for at least 7 days to kill parasites; homefreezers may not be cold enough.^[47][48]

Historically, fish that live all or part of their lives infresh water were considered unsuitable for sashimi due to the possibility of parasites (seeSashimi article). Parasitic infections from freshwater fish are a serious problem in some parts of the world, particularlySoutheast Asia^{[citation needed]}. Fish that spend part of their life cycle inbrackish or fresh water, likesalmon (ananadromous coastalfish closely related totrout), are a particular problem. A study inSeattle, Washington showed that 100% of wild salmon hadroundwormlarvae capable of infecting people. In the same studyfarm-raised salmon did not have any roundworm larvae.^[49]

Parasite infection from raw fish is rare in thedeveloped world (fewer than 40 cases per year in theUnited States^{[citation needed]}), and involves mainly three kinds of parasites:Clonorchis sinensis (atrematode/fluke),Anisakis (anematode/roundworm) andDiphyllobothrium (acestode/tapeworm). Infection risk ofAnisakis is particularly high in fish which may have lived in a river or estuary, such as salmon (sa ke inJapanese cuisine) ormackerel (sa ba in Japanese cuisine). Such parasite infections can generally be avoided byboiling,grilling,preserving in salt or vinegar, or deep-freezing. In Japan, it is common to eat raw salmon andikura (roe), but these foods are frozen overnight prior to eating to prevent infections from parasites, particularlyAnisakis.^{[citation needed]}

The neologism "pescetarian" covers those who eat fish and otherseafood, but not mammals and birds.^[50]

A 1999metastudy combined data from five studies from western countries. The metastudy reportedmortality ratios, where lower numbers indicated fewer deaths, for pescetarians to be 0.82, vegetarians to be 0.84, and occasional meat eaters to be 0.84. Regular meat eaters and vegans shared the highest mortality ratio of 1.00. However, the "lower mortality was due largely to the relatively low prevalence of smoking in these [vegetarian] cohorts".^[51]

Since fish is animal flesh, theVegetarian Society has stated that vegetarian diets cannot contain fish.^[52]

Religious rites and rituals regarding food also tend to classify the birds of the air and the fish of the sea separately from land-bound mammals.^[53] Sea-bound mammals are often treated as fish under religious laws – as in Jewish dietary law, which forbids the eating ofcetacean meat, such as whale, dolphin or porpoise, because they are not "fish with fins and scales"; nor, as mammals, do they chew their cud and have cloven hooves, as required byLeviticus 11:9–12.Jewish (kosher) practice treats fish differently from other animal foods. The distinction between fish and "meat" is codified by the Jewish dietary law ofkashrut, regarding the mixing of milk and meat, which does not forbid the mixing of milk and fish. Modern Jewish legal practice (halakha) onkashrut classifies the flesh of both mammals and birds as "meat"; fish are considered to beparve, neither meat nor a dairy food. (The preceding portion refers only to the halakha ofAshkenazi Jews;Sephardic Jews do not mix fish with dairy.)^{[citation needed]}

Ichthys has become asymbol of Christianity since ancient times. In theNew Testament Luke 24 – Jesus's eating of a fish^{[Luke 24]} and Jesus telling his disciples where to catch fish, before cooking it for them to eat. Seasonal religious prohibitions against eating meat do not usually include fish. For example, non-fish meat was forbidden duringLent and on all Fridays of the year in pre-Vatican IIRoman Catholicism, but fish was permitted (as were eggs). (SeeFasting in Catholicism.) InEastern Orthodoxy, fish is permitted on some fast days when other meat is forbidden, but stricter fast days also prohibit fish with spines, while permittinginvertebrate seafood such asshrimp andoysters, considering them "fish without blood".^{[citation needed]}

SomeBuddhists andHindus (Brahmins ofWest Bengal,Odisha and Saraswat Brahmins of theKonkan) abjure meat that is not fish.Muslim (halal) practice also treats fish differently from other animal foods, as it can be eaten without requiring the ritualistic slaughter that is prescribed for other halal animals.^[54]

Among theSomali people, mostclans have a taboo against the consumption of fish, and do not intermarry with the few occupational clans that do eat it.^[55][56]

There are taboos on eating fish among many uplandpastoralists andagriculturalists (and even some coastal peoples) inhabiting parts of southeasternEgypt,Ethiopia,Eritrea,Somalia,Kenya, and northernTanzania. This is sometimes referred to as the "Cushitic fish-taboo", as Cushitic speakers are believed to have been responsible for the introduction of fish avoidance toEast Africa, though not all Cushitic groups avoid fish. The zone of the fish taboo roughly coincides with the area whereCushitic languages are spoken, and as a general rule, speakers ofNilo-Saharan andSemitic languages do not have this taboo, and indeed many are watermen.^[56][57] The fewBantu andNilotic groups in East Africa that do practice fish avoidance also reside in areas whereCushites appear to have lived in earlier times. Within East Africa, the fish taboo is found no further than Tanzania. This is attributed to the local presence of thetsetse fly and in areas beyond, which likely acted as a barrier to further southern migrations bywandering pastoralists, the principal fish-avoiders.Zambia andMozambique's Bantus were therefore spared subjugation by pastoral groups, and they consequently nearly all consume fish.^[56]

There is also another center of fish avoidance inSouthern Africa, among mainlyBantu speakers. It is not clear whether this disinclination developed independently or whether it was introduced. It is certain, however, that no avoidance of fish occurs among southern Africa's earliest inhabitants, theKhoisan. Nevertheless, since the Bantu of southern Africa also share various cultural traits with the pastoralists further north in East Africa, it is believed that, at an unknown date, the taboo against the consumption of fish was similarly introduced from East Africa by cattle-herding peoples who somehow managed to get their livestock past the aforementioned tsetse fly endemic regions.^[56]

Certain species of fish are also forbidden in Judaism such as the freshwatereel (Anguillidae) and all species ofcatfish. Although they live in water, they appear to have no fins or scales (except under a microscope) (see Leviticus 11:10–13^[58]). Sunni Muslim laws are more flexible in this and catfish and shark are generally seen as halal as they are special types of fish. Eel is generally considered permissible in the four Sunnimadh'hab, but the Ja'fari jurisprudence followed by most Shia Muslims forbids it.^[59][60][61]

Many tribes of theSouthwestern United States, including theNavaho,Apache, andZuñi, have a taboo against fish and other water-related animals, includingwaterfowl.^[62]

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• Science Daily Benefits Of Eating Fish Greatly Outweigh The Risks, New Study Says
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• Scientific American Soy and fish protect from cancer: study.
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