Fish is a food consumed by many species, including humans. The word "fish" refers to both the animal and to the food prepared from it. In culinary and fishery contexts, the term fish also includes shellfish, such as molluscs, crustaceans and echinoderms. Fish has been an important source of protein for humans throughout recorded history. Health hazards Fish is the most common food to obstruct the airway and cause choking. Choking on fish was responsible for about reported 4,500 accidents in the UK in 1998. Allergens A seafood allergy is a hypersensitivity to an allergen which can be present in fish, 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. A lot of fish eat algae and other organisms that contain biotoxins (defensive substances against predators). Biotoxins accumulated in fish/shellfish include brevetoxins, okadaic acid, sa
itoxins, 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. 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 senseЧthe flesh of mammalian species (pigs, cattle, etc.) raised and prepared for human consumption, to the exclusion of fish and poultry. Vegetarians don't eat fish, and consider that fish is meat, since it is the flesh of an animal. 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 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). However, this is an incorrect assumption, as fish are often raised in artificial environments, with the same types of cramped, unnatural, and often unsanitary conditions that land animals are raised in. 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.