Fish as food

This article is about fish as food for humans. For sealife in general as food, see seafood. For fish fed to other fish, see commercial fish feed and aquarium fish feed.

Redbelly tilapia presented as food

Fish is consumed as a food by many species, including humans. It has been an important source of protein and other nutrients for humans throughout recorded history.

In culinary and fishery contexts, the term fish can also include shellfish, such as molluscs, crustaceans and echinoderms. English does not distinguish between fish as an animal and the food prepared from it, as it does with pig vs. pork or cow vs. beef. Some other languages do, as in the Spanish peces versus pescado. The modern English word for fish comes from the Old English word fisc (plural: fiscas) which was pronounced as it is today. English also has the term seafood, which covers fish found in the seas and oceans as well as other marine life used as food.

Species

Over 32,000 species of fish have been described, making them the most diverse group of vertebrates. In addition, there are many species of shellfish. However, only a small number of species are commonly eaten by humans.

Preparation

See also: Fish processing

Fish can be prepared in a variety of ways. It can be uncooked (raw) (cf. sashimi). It can be cured by marinating (cf. escabeche), pickling (cf. pickled herring), or smoking (cf. smoked salmon). Or it can be cooked by baking, frying (cf. fish and chips), grilling, poaching (cf. court-bouillon), or steaming. 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.

Nutritional value

Comparison of nutrients in 100 g of whitefish or oily fish
Nutrient	Whitefish Alaska pollock	Oily fish Atlantic herring	Halibut fillet (a whitefish) on top of a salmon fillet (an oily fish)
Energy (kcal)	111	203
Protein (g)	23	23
Fat (g)	1	12
Cholesterol (mg)	86	77
Vitamin B-12 (µg)	4	13
Phosphorus (mg)	267	303
Selenium (µg)	44	47
Omega-3 (mg)	509	2014

"Fish provides a good source of high quality protein and contains many vitamins and minerals. It may be classed as either whitefish, oily 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."

Health benefits

See also: Health benefits of eating seafood

Research over the past few decades has shown that the nutrients and minerals in fish, and particularly the omega-3 fatty acids found in pelagic fishes, are heart-friendly and can make improvements in brain development and reproduction. This has highlighted the role for fish in the functionality of the human body.

Health hazards

Fish is the most common food to obstruct the airway and cause choking. Choking on fish was responsible for about 4,500 reported accidents in the UK in 1998.

Allergens

A seafood allergy is a hypersensitivity to an allergen which can be present in fish, and particularly in shellfish. This can result in an overreaction of the immune system and lead to severe physical symptoms. Most people who have a food allergy also have a seafood allergy. Allergic reactions can result from ingesting seafood, or by breathing in vapours from preparing or cooking seafood. The most severe seafood allergy reaction is anaphylaxis, an emergency requiring immediate attention. It is treated with epinephrine.

Specially prepared dish of the poisonous blowfish fugu, Japan

Biotoxins

Some species of fish, notably the puffer fugu used for sushi, and some kinds of shellfish, can result in serious poisoning if not prepared properly. These fish always contain these poisons as a defense against predators; it is not present due to environmental circumstances. Particularly, fugu has a lethal dose of tetrodotoxin in its internal organs and must be prepared by a licensed fugu chef who has passed the national examination in Japan. Ciguatera poisoning can occur from eating larger fish from warm tropical waters, such as sea bass, grouper, and red snapper. Scombroid poisoning can result from eating large oily fish which have sat around for too long before being refrigerated or frozen. This includes scombroids such as tuna and mackerel, but can also include non-scombroids such as mahi-mahi and amberjack. The poison is odourless and tasteless.

Many fish eat algae and other organisms that contain biotoxins (defensive substances against predators). Biotoxins accumulated in fish/shellfish include brevetoxins, okadaic acid, saxitoxins, ciguatoxin and domoic 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 cause diarrhea, dizzyness and a (temporary) feeling of claustrophobia.

Shellfish are filter feeders and, therefore, accumulate toxins produced by microscopic algae, such as dinoflagellates and diatoms, and cyanobacteria. There are four syndromes called shellfish poisoning which can result in humans, sea mammals, and birds from the ingestion of toxic shellfish. These are primarily associated with bivalve molluscs, such as mussels, clams, oysters and scallops. Fish, like anchovies can also concentrate toxins such as domoic acid. If suspected, medical attention should be sought.

fish and shellfish poisoning
	poisoning type	symptoms	duration	toxin	antidote	sources
fish	Ciguatera	Nausea, vomiting and diarrhea, usually followed by headaches, muscle aches, paresthesia, numbness, ataxia, vertigo, and hallucinations.	weeks to years	ciguatoxin and similar: maitotoxin, scaritoxin and palytoxin	none known
	Scombroid food poisoning	Skin flushing, throbbing headache, oral burning, abdominal cramps, nausea, diarrhea, palpitations, sense of unease, and, rarely, collapse or loss of vision. Symptoms occur usually within 10–30 minutes of ingesting spoiled fish.	usually four to six hours	histamine, possibly others	Oral anti-histamines
	Haff disease	Rhabdomyolysis, that is, a swelling and breakdown of skeletal muscle (with a risk of acute kidney failure) within 24 hours after consuming fish		a toxic cause is suspected but has not been proven	none known
	Ichthyo- allyeinotoxism	Vivid auditory and visual hallucinations similar in some aspects to LSD.	can last for several days
shellfish	Amnesic	Permanent short-term memory loss and brain damage	fatal in severe cases	domoic acid, which acts as a neurotoxin	none known
	Diarrheal	diarrhea and possibly nausea, vomiting and cramps.	symptoms usually set in within half an hour and last about a day	okadaic acid, which inhibits intestinal cellular de-phosphorylation.
	Neurotoxic	Vomiting and nausea and a variety of neurological symptoms such as slurred speech. Not fatal though it may require hospitalization.		Brevetoxins or brevetoxin analogs
	Paralytic	Includes nausea, vomiting, diarrhea, abdominal pain, and tingling or burning sensations. Other symptoms also possible.	occasionally fatal	principal toxin saxitoxin

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.

Mercury and other toxic metals

Main article: Mercury in fish

Fish products have been shown to contain varying amounts of heavy or toxic metals. Toxicity is a function of solubility, and insoluble compounds often exhibit negligible toxicity. Organometallic forms such as dimethyl mercury and tetraethyl lead can be extremely toxic.

mercury/omega-3 levels
omega-3 ↓	low mercury < 0.04 ppm	medium mercury 0.04–0.40 ppm	high mercury > 0.40 ppm
high > 1.0%	salmon sardine	Atlantic mackerel flatfish halibut herring	Spanish mackerel swordfish tilefish
medium 0.4–1.0%	pollock	hoki tuna	king mackerel shark
low < 0.4%	catfish shrimp	cod snapper tuna canned light	grouper orange roughy

mercury/omega-3 levels in commercial fish and shellfish
	species	mercury (mean ppm)	omega-3 (mean percent)	habitat	notes	trophic level	max age (years)
	Tilefish	1.450	1.06	pelagic		3.6	35
	Swordfish	0.995	1.14	pelagic		4.5	15
	Shark	0.979	0.98	pelagic
	King mackerel	0.730	0.42	pelagic		4.5	14
	Orange roughy	0.571	0.033	demersal		4.3	149
	Marlin	0.485 *		pelagic		4.5
	Mackerel (Spanish)	0.454	1.65	pelagic		4.5	5
	Grouper	0.448	0.27	demersal		4.2
	Tuna	0.391	0.77	pelagic	All species, fresh/frozen
	Patagonian toothfish	0.354		demersal		4.0	50+
	Halibut	0.241	1.01	demersal		4.3
	Snapper	0.166	0.26	demersal
	Bass	0.152		demersal		3.9
	Perch	0.150		freshwater		4.0
	Tuna	0.128	0.24	pelagic	All species, canned, light
	Perch (ocean)	0.121 *		demersal
	Cod	0.111	0.23	demersal		3.9	22
	Carp	0.110		freshwater
	Lobster (American)	0.107		demersal
	Lobster (spiny)	0.093		demersal
	Whitefish	0.089		demersal
	Herring	0.084	1.94	pelagic		3.2	21
	Trout	0.071		freshwater
	Crab	0.065		demersal	Blue, king and snow crab
	Hoki (blue grenadier)	0.058	0.48	demersal		3.5
	Flatfish	0.056 *	0.56	demersal	Flounder, plaice and sole
	Haddock	0.055		demersal	Atlantic
	Atlantic mackerel	0.050	1.64	pelagic
	Mullet	0.050		pelagic
	Pollock	0.031	0.53	demersal
	Catfish	0.025	0.31	demersal		3.9	24
	Squid	0.023		pelagic
	Salmon	0.022 *	1.76	pelagic	Fresh/frozen
	Anchovies	0.017		pelagic		3.1
	Sardine	0.013	1.94	pelagic		2.7
	Tilapia *	0.013		freshwater
	Oyster	0.012		demersal
	Clam *	0.009		demersal
	Salmon	0.008 *		pelagic	Canned
	Scallop	0.003		demersal
	Shrimp	0.001 *	0.12	demersal			6.5
	Greenshell mussel		0.35	demersal
	Sydney rock oyster		1.11	demersal
* indicates methylmercury only was analyzed (all other results are for total mercury)

According to the US Food and Drug Administration (FDA), the risk from mercury by eating fish and shellfish is not a health concern for most people. 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 eat shark, swordfish, king mackerel, or tilefish because they contain high levels of mercury.
2. Eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury. Four of the most commonly eaten fish that are low in mercury are canned light tuna, salmon, pollock, and catfish. 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 don't consume any other fish during that week.

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

Mislabelling

When the ocean conservation organization Oceana 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.

Persistent organic pollutants

See also: Marine pollution § Toxins

If fish and shellfish inhabit polluted waters, they can accumulate other toxic chemicals, particularly fat-soluble pollutants containing chlorine or bromine, dioxins or PCBs. Fish that is to be eaten should be caught in unpolluted water. Some organisations such as SeafoodWatch, RIKILT, Environmental Defense Fund, IMARES provide information on species that do not accumulate much toxins/metals.

Parasites

Differential symptoms of parasite infections by raw fish. All have gastrointestinal, but otherwise distinct, symptoms.

See also: Fish diseases and parasites

Parasites in fish are a natural occurrence and common. Though not a health concern in thoroughly cooked fish, parasites are a concern when consumers eat raw or lightly preserved fish such as sashimi, sushi, ceviche, and gravlax. 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. Home freezers may not be cold enough to kill parasites.

Traditionally, fish that live all or part of their lives in fresh water were considered unsuitable for sashimi due to the possibility of parasites (see Sashimi article). Parasitic infections from freshwater fish are a serious problem in some parts of the world, particularly Southeast Asia. Fish that spend part of their life cycle in brackish or fresh water, like salmon, are a particular problem. A study in Seattle, Washington showed that 100% of wild salmon had roundworm larvae capable of infecting people. In the same study farm-raised salmon did not have any roundworm larvae.

Parasite infection by raw fish is rare in the developed world (fewer than 40 cases per year in the U.S.), and involves mainly three kinds of parasites: Clonorchis sinensis (a trematode/fluke), Anisakis (a nematode/roundworm) and Diphyllobothrium (a cestode/tapeworm). Infection risk of anisakis is particularly higher in fishes which may live in a river such as salmon (sake) in Salmonidae or mackerel (saba). Such parasite infections can generally be avoided by boiling, burning, preserving in salt or vinegar, or freezing overnight. In Japan it is common to eat raw salmon and ikura, but these foods are frozen overnight prior to eating to prevent infections from parasites, particularly anisakis.

Fish, meat and vegetarians

Hawaiian food: Seared ahi and wasabi beurre blanc sauce

Nutritional content of fish compared to meat
110 grams (4 oz or .25 lb)

Source	calories	protein	carbs	fat
fish	110–140	20–25 g	0 g	1–5 g
chicken breast	160	28 g	0 g	7 g
lamb	250	30 g	0 g	14 g
steak (beef top round)	210	36 g	0 g	7 g
steak (beef T-bone)	450	25 g	0 g	35 g

Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat, but it may also describe other edible organs and tissues. The term meat is used by the meat packing industry in a more restrictive sense—the flesh of mammalian species (pigs, cattle, etc.) raised and prepared for human consumption, to the exclusion of fish and poultry.

Vegetarians do not eat fish, and consider that fish is meat, since it is the flesh of an animal. Vegans or strict vegetarians refrain from consuming any animal products, not only meat and fish but, in contrast to ovo-lacto vegetarians, eggs, dairy products and all other animal-derived substances.

However, pescetarians eat fish and other seafood, but not mammals and birds. The Merriam-Webster dictionary dates the origin of the term pescetarian to 1993 and defines it to mean: "one whose diet includes fish but no other meat." Pescatarians may consume fish based solely upon the idea that the fish are not factory farmed as land animals are (i.e., their problem is with the capitalist-industrial production of meat, not with the consumption of animal foods themselves). Some eat fish with the justification that fish have less sophisticated nervous systems than land-dwelling animals. Others may choose to consume only wild fish based upon the lack of confinement, while choosing to not consume fish that have been farmed.

A 1999 metastudy combined data from five studies from western countries. The metastudy reported mortality ratios, where lower numbers indicated fewer deaths, for pescetarians (fish eaters) to be 0.82, vegetarians to be 0.84, occasional meat eaters to be 0.84. Regular meat eaters and vegans shared the highest mortality ratio of 1.00. The study reported the numbers of deaths in each category, and expected error ranges for each ratio, and adjustments made to the data. However, the "lower mortality was due largely to the relatively low prevalence of smoking in these [vegetarian] cohorts".

In religion

Smoked salmon

See also: Kosher fish

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. Sea-bound mammals are often treated as fish under religious laws - as in Jewish dietary law, which forbids the eating of cetacean 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 by Leviticus 11:9–12. Jewish (kosher) practice treat fish differently from other animal foods. The distinction between fish and "meat" is codified by the Jewish dietary law of kashrut, regarding the mixing of milk and meat, which does not forbid the mixing of milk and fish. Modern Jewish legal practice (halakha) on kashrut classifies the flesh of both mammals and birds as "meat"; fish are considered to be parve, neither meat nor a dairy food. (The preceding portion refers only to the halakha of Ashkenazi Jews, Sephardic Jews do not mix fish with dairy)

Seasonal religious prohibitions against eating meat do not usually include fish. For example, non-fish meat was forbidden during Lent and on all Fridays of the year in pre-Vatican II Roman Catholicism, but fish was permitted (as were eggs). (See Fasting in Catholicism.) In Eastern Orthodoxy, fish is permitted on some fast days when other meat is forbidden, but stricter fast days also prohibit fish with spines, while permitting invertebrate seafood such as shrimp and oysters, considering them "fish without blood."

Some Buddhists and Hindus (Brahmins of West Bengal, Odisha and Saraswat Brahmins of the Konkan) abjure meat that is not fish. Muslim (halal) practice also treats fish differently from other animal foods, as it can be eaten.

Taboos on eating fish

See also: Taboo food and drink § Fish

Among the Somali people, most clans have a taboo against the consumption of fish, and do not intermarry with the few occupational clans that do eat it.

There are taboos on eating fish among many upland pastoralists and agriculturalists (and even some coastal peoples) inhabiting parts of southeastern Egypt, Ethiopia, Eritrea, Somalia, Kenya, and northern Tanzania. 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 to East Africa, though not all Cushitic groups avoid fish. The zone of the fish taboo roughly coincides with the area where Cushitic languages are spoken, and as a general rule, speakers of Nilo-Saharan and Semitic languages do not have this taboo, and indeed many are watermen. The few Bantu and Nilotic groups in East Africa that do practice fish avoidance also reside in areas where Cushites 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 the tsetse fly and in areas beyond, which likely acted as a barrier to further southern migrations by wandering pastoralists, the principal fish-avoiders. Zambia and Mozambique's Bantus were therefore spared subjugation by pastoral groups, and they consequently nearly all consume fish.

There is also another center of fish avoidance in Southern Africa, among mainly Bantu 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, the Khoisan. 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.

Certain species of fish are also forbidden in Judaism such as the freshwater eel (Anguillidae) and all species of catfish. Although they live in water, they appear to have no fins or scales (except under a microscope) (see Leviticus 11:10-13). 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 Sunni madh'hab, but the Ja'fari jurisprudence followed by most Shia Muslims forbids it.

Many tribes of the Southwestern United States, including the Navaho, Apache, and Zuñi, have a taboo against fish and other water-related animals, including waterfowl.

Dishes

• Bokkoms
• Bouillabaisse
• Bourdeto
• Ceviche
• Cioppino
• Crab stick
• Crappit heid
• Croquette
• Curanto
• Dressed herring
• Fish and chips
• Fish ball
• Fish slice
• Fishcake
• Fish chowder
• Fishstick
• Gefilte fish
• Kamaboko
• Kipper
• Lox
• Paella
• Poke (Hawaii)
• Pompano en Papillote
• Quenelles Lyonnaises
• Rakfisk
• Remoulade
• Rissole
• Sashimi
• Seafood birdsnest
• Smoked salmon
• Soused herring
• Stargazy pie
• Surimi
• Surströmming
• Sushi
• Tuna fish sandwich
• Ukha

See also

• Anisakis
• Boneless fish
• Boning knife
• Fish head
• Fish products
• Fishmonger
• Got Mercury?
• Ichthyoallyeinotoxism
• Kudoa thyrsites
• List of fish dishes
• List of foods
• List of harvested aquatic animals by weight
• List of seafood dishes
• Oily fish
• Oroshi hocho
• Pescetarianism
• Phosphatidylserine
• Seafood Watch

References

• Aquamedia, "Consumption of Fishery Products" retrieved from http://www.feap.info/economics/Tradebalance_en.asp on 2007-09-17.
• Paston-Williams, Sara (2006) Fish: Recipes from a Busy Island National Trust Books. ISBN 9781905400072.
• Sweetser, Wendy (2009) The Connoisseur's Guide to Fish & Seafood Sterling Publishing Company,. ISBN 9781402770517.
• University of Michigan Health System, "Fish & Seafood" retrieved from http://www.med.umich.edu/umim/clinical/pyramid/fish.htm on 2007-09-17.
• VegDining.com, "Frequently Asked Questions-Definitions" retrieved from http://www.ivu.org/faq/definitions.html on 2007-09-17.
• The State of World Fisheries and Aquaculture 2000, 2000, retrieved from http://www.who.int/nutrition/topics/3_foodconsumption/en/index5.html on 2007-11-17. World Health Organization.

External links

• Science Daily Benefits Of Eating Fish Greatly Outweigh The Risks, New Study Says
• Science Daily Experts Say Consumers Can Eat Around Toxins In Fish
• Scientific American Soy and fish protect from cancer: study.
• Seafood Recipes from Gourmet Recipe.