Fish as food
Many species of fish are caught by humans and consumed as food in virtually all regions around the world. Their meat has been an important dietary source of protein and other nutrients in the human diet.
The English language does not have a special culinary name for food prepared from fish like with other animals, or as in other languages. In culinary and fishery contexts, fish may include so-called shellfish such as molluscs, crustaceans, and echinoderms; but, more expansively, seafood covers both fish and other marine life used as food.
Since 1961, the average annual increase in global apparent food fish consumption has outpaced population growth and exceeded the increase in consumption of meat from all terrestrial animals except poultry, both combined and individually. In per capita terms, food fish consumption has grown from in 1961, to in 2015, at an average rate of about 1.5 percent per year. The expansion in consumption has been driven not only by increased production, but also by a combination of many other factors, including reduced wastage, better utilization, improved distribution channels and growing consumer demand, linked with population growth, rising disposable incomes and urbanization.
Europe, Japan and the United States 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, while Oceania and Africa consumed the lowest share. The shift is the result of structural changes in the sector, and the growing role of Asian countries in fish production in particular, 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.
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
Fish can be prepared in a variety of ways. It can be served uncooked ; cured by marinating, pickling or smoking ; or cooked by baking, frying, grilling, poaching 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.Compared to meat, fish has a relatively delicate texture derived from short fibers separated by large sheets and thin connective tissue.
The British historian William Radcliffe wrote in Fishing from the Earliest Times:
"The Emperor Domitian ordered a special sitting of the Senate to deliberate and advise on a matter of such grave State importance as the best method of cooking a turbot."
Nutritional value
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. 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 in small island developing States.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 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 and essential fatty acids, all of which are vital for the healthy functioning of the body."
Health benefits
Eating oily fish containing long-chain omega-3 fatty acids may reduce systemic inflammation and lower the risk of cardiovascular disease. Eating about of oily fish rich in omega-3 fatty acids once per week is a recommended consumption amount. Increasing intake of omega-3 fatty acids may slightly reduce the risk of a fatal heart attack, but likely has little effect on the overall number of deaths from cardiovascular disease.Health hazards
is the most common food-related foreign body to cause airway obstruction. Choking on fish was responsible for about 4,500 reported accidents in the United Kingdom in 1998.Allergens
A seafood allergy is a food allergy to allergens which can be present in fish. This can result in an overreaction of the immune system and lead to severe physical symptoms from urticaria to angioedema and distributive shock. Allergic reactions can result from ingesting seafood, or by breathing in vapours from preparing or cooking seafood. The most severe allergic reaction is anaphylaxis, a medical emergency requiring immediate attention and is treated urgently with epinephrine.Biotoxins
Some species of fish, notably the fugu pufferfish used for sushi, can result in serious food poisoning if not prepared properly. These fish always contain toxins as a natural 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, barracuda 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 often odourless and tasteless.Many fish eat algae and other organisms that contain biotoxins, which are 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, dizziness and a 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 seabirds 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.
| 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 | |
| Fish | 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 | |
| Fish | Haff disease | Rhabdomyolysis, that is, a swelling and breakdown of skeletal muscle within 24 hours after consuming fish | A toxic cause is suspected but has not been proven | None known | ||
| Fish | 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 | |
| Shellfish | 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. | ||
| Shellfish | 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 | |||
| Shellfish | Paralytic | Includes nausea, vomiting, diarrhea, abdominal pain, and tingling or burning sensations. Other symptoms also possible. | Occasionally fatal | Principal toxin saxitoxin | 4-Aminopyridine has been used in non-human animals. |
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
Fish products, especially those from apex and higher-order consumers up the food chain, have been shown to contain varying amounts of heavy or toxic metals due to biomagnification. 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.According to the US Food and Drug Administration, 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:
- Do not eat shark, swordfish, king mackerel, or tilefish because they contain high levels of mercury.
- Eat up to 12 ounces 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 has more mercury than canned light tuna. So, when choosing your two meals of fish and shellfish, you may eat up to 6 ounces of albacore tuna per week.
- 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 per week of fish you catch from local waters, but do not consume any other fish during that week.