Fish

Afish(pl.:fishorfishes) is anaquatic,anamniotic,gill-bearingvertebrateanimalwith swimmingfinsanda hard skull, but lackinglimbswithdigits. Fish can be grouped into the morebasaljawless fishand the more commonjawed fish, the latter including alllivingcartilaginousandbony fish, as well as the extinctplacodermsandacanthodians. In a break to the long tradition of grouping all fish into a singleclass(Pisces), contemporaryphylogeneticsviews fish as aparaphyleticgroup.
Most fish arecold-blooded, their body temperature varying with the surrounding water, though some largeactive swimmerslikewhite sharkandtunacan hold a highercore temperature. Many fish cancommunicate acousticallywith each other, such as duringcourtship displays. The study of fish is known asichthyology.
The earliest fish appeared during theCambrianas smallfilter feeders; they continued toevolvethrough thePaleozoic, diversifying into many forms. The earliest fish with dedicated respiratory gills andpaired fins, theostracoderms, had heavybony platesthat served as protectiveexoskeletonsagainstinvertebratepredators. The first fish withjaws, the placoderms, appeared in theSilurianand greatly diversified during theDevonian, the "Age of Fishes".
Bony fish, distinguished by the presence ofswim bladdersand laterossifiedendoskeletons, emerged as thedominantgroup of fish after theend-Devonian extinctionwiped out theapex predators, the placoderms. Bony fish are further divided into thelobe-finnedandray-finned fish. About 96% of all living fish species today areteleosts, acrown groupof ray-finned fish that canprotrude their jaws. Thetetrapods, a mostlyterrestrialcladeof vertebrates that have dominated the toptrophic levelsin bothaquaticandterrestrial ecosystemssince the LatePaleozoic, evolved from lobe-finned fish during theCarboniferous, developing air-breathinglungshomologousto swim bladders. Despite thecladisticlineage, tetrapods are usually not considered to be fish.
Fish have been an importantnatural resourceforhumanssinceprehistorictimes, especiallyas food.Commercialandsubsistence fishersharvest fish inwild fisheriesorfarmthem inpondsor inbreeding cagesin the ocean. Fish are caught forrecreation, or raised byfishkeepersasornamentsfor private and public exhibition inaquariaandgarden ponds. Fish have had a role inhuman culturethrough the ages, serving asdeities, religious symbols, and as the subjects of art, books and movies.
The wordfishis inherited fromProto-Germanic, and is related toGermanFisch, theLatinpiscisandOld Irishīasc, though the exact root is unknown; some authorities reconstruct aProto-Indo-Europeanroot*peysk-, attested only inItalic,Celtic, andGermanic.
About 530 million years ago during theCambrian explosion, fishlike animals with anotochordand eyes at the front of the body, such asHaikouichthys, appear in thefossil record.During the lateCambrian, other jawless forms such asconodontsappear.
Jawed vertebratesappear in theSilurian, with giant armouredplacodermssuch asDunkleosteus.Jawed fish, too, appeared during the Silurian:the cartilaginousChondrichthyesand the bonyOsteichthyes.
During theDevonian, fish diversity greatly increased, including among the placoderms, lobe-finned fishes, and early sharks, earning the Devonian the epithet "the age of fishes".
Fishes are aparaphyleticgroup, since anycladecontaining all fish, such as theGnathostomataor (for bony fish)Osteichthyes, also contains the clade oftetrapods(four-limbed vertebrates, mostly terrestrial), which are usually not considered fish.Some tetrapods, such ascetaceansandichthyosaurs, havesecondarily acquireda fish-like body shape throughconvergent evolution.Fishes of the Worldcomments that "it is increasingly widely accepted that tetrapods, including ourselves, are simply modified bony fishes, and so we are comfortable with using the taxon Osteichthyes as a clade, which now includes all tetrapods".Thebiodiversityof extant fish is unevenly distributed among the various groups;teleosts, bony fishesable to protrude their jaws, make up 96% of fish species.Thecladogramshows theevolutionary relationshipsof all groups of living fishes (with their respective diversity) and the tetrapods.Extinctgroups are marked with adagger(†); groups of uncertain placementare labelled with a question mark (?) and dashed lines (- - - - -).
Fishes (without tetrapods) are aparaphyleticgroup and for this reason, the classPiscesseen in older reference works is no longer used in formal classifications. Traditional classification divides fish into threeextantclasses(Agnatha, Chondrichthyes, and Osteichthyes), and with extinct forms sometimes classified within those groups, sometimes as their own classes.
Fish account for more than half of vertebrate species. As of 2016, there are over 32,000 described species of bony fish, over 1,100 species of cartilaginous fish, and over 100 hagfish and lampreys. A third of these fall within the nine largest families; from largest to smallest, these areCyprinidae,Gobiidae,Cichlidae,Characidae,Loricariidae,Balitoridae,Serranidae,Labridae, andScorpaenidae. About 64 families aremonotypic, containing only one species.
Fish range in size from the huge 16-metre (52 ft)whale sharkto some tiny teleosts only 8-millimetre (0.3 in) long, such as the cyprinidPaedocypris progeneticaand thestout infantfish.
Swimming performance varies from fish such as tuna,salmon, andjacksthat can cover 10–20 body-lengths per second to species such aseelsandraysthat swim no more than 0.5 body-lengths per second.
A typical fish iscold-blooded, has astreamlinedbody for rapid swimming, extracts oxygen from water using gills, has two sets of paired fins, one or two dorsal fins, an anal fin and a tail fin, jaws,  skin covered withscales, and lays eggs. Each criterion has exceptions, creating a wide diversity in body shape and way of life. For example, some fast-swimming fish are warm-blooded, while some slow-swimming fish have abandoned streamlining in favour of other body shapes.
Fish species are roughly divided equally betweenfreshwaterand marine (oceanic) ecosystems; there are some 15,200 freshwater species and around 14,800 marine species.Coral reefsin theIndo-Pacificconstitute the center of diversity for marine fishes,whereas continental freshwater fishes are most diverse in largeriver basinsoftropical rainforests, especially theAmazon,Congo, andMekongbasins.More than 5,600 fish species inhabitNeotropicalfreshwaters alone, such thatNeotropical fishesrepresent about 10% of allvertebratespecies on the Earth.
Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from highmountain streams(e.g.,charandgudgeon) to theabyssaland evenhadaldepths of the deepest oceans (e.g.,cusk-eelsandsnailfish), although none have been found in the deepest 25% of the ocean.The deepest living fish in the ocean so far found is a cusk-eel,Abyssobrotula galatheae, recorded at the bottom of thePuerto Rico Trenchat 8,370 m (27,460 ft).
In terms of temperature,Jonah's icefishlive in coldwaters of the Southern Ocean, including under theFilchner–Ronne Ice Shelfat a latitude of 79°S,whiledesert pupfishlive in desert springs, streams, and marshes, sometimes highly saline, with water temperatures as high as 36 C.
A few fish live mostly on land or lay their eggs on land near water.Mudskippersfeed and interact with one another on mudflats and go underwater to hide in their burrows.A singleundescribed speciesofPhreatobiushas been called a true "land fish" as this worm-like catfish strictly lives among waterloggedleaf litter.Cavefishof multiple families live inunderground lakes,underground riversoraquifers.
Like other animals, fish suffer fromparasitism. Some species usecleaner fishto remove external parasites. The best known of these are thebluestreak cleaner wrassesofcoral reefsin theIndianandPacificoceans. These small fish maintain cleaning stations where other fish congregate and perform specific movements to attract the attention of the cleaners.Cleaning behaviors have been observed in a number of fish groups, including an interesting case between two cichlids of the same genus,Etroplus maculatus, the cleaner, and the much largerE. suratensis.
Fish occupy manytrophic levelsin freshwater and marinefood webs. Fish at the higher levelsare predatory, and a substantial part of their prey consists of other fish.In addition, mammals such asdolphinsandsealsfeed on fish, alongside birds such asgannetsandcormorants.
The body of a typical fish is adapted for efficient swimming by alternately contracting paired sets ofmuscleson either side of the backbone. These contractions form S-shaped curves that move down the body. As each curve reaches the tail fin, force is applied to the water, moving the fish forward. The other fins act ascontrol surfaceslike an aircraft's flaps, enabling the fish to steer in any direction.
Since body tissue is denser than water, fish must compensate for the difference or they will sink. Many bony fish have an internal organ called aswim bladderthat allows them to adjust theirbuoyancyby increasing or decreasing the amount of gas it contains.
Thescales of fishprovide protection frompredatorsat the cost of adding stiffness and weight.Fish scales are often highly reflective; thissilvering provides camouflagein the open ocean. Because the water all around is the same colour, reflecting an image of the water offers near-invisibility.
Fish have aclosed-loop circulatory system. Theheartpumps the blood in a single loop throughout the body; for comparison, the mammal heart has two loops, one for the lungs to pick up oxygen, one for the body to deliver the oxygen. In fish, the heart pumps blood through the gills. Oxygen-rich blood then flows without further pumping, unlike in mammals, to the body tissues. Finally, oxygen-depleted blood returns to the heart.
Fish exchange gases usinggillson either side of thepharynx. Gills consist of comblike structures called filaments. Each filament contains acapillarynetwork that provides a largesurface areafor exchangingoxygenandcarbon dioxide. Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. Capillary blood in the gills flows in the opposite direction to the water, resulting in efficientcountercurrent exchange. The gills push the oxygen-poor water out through openings in the sides of the pharynx. Cartilaginous fish have multiple gill openings: sharks usually have five, sometimes six or seven pairs; they often have to swim to oxygenate their gills. Bony fish have a single gill opening on each side, hidden beneath a protective bony cover oroperculum. They are able to oxygenate their gills using muscles in the head.
Some 400 species of fish in 50 families can breathe air, enabling them to live in oxygen-poor water or to emerge on to land.The ability of fish to do this is potentially limited by their single-loop circulation, as oxygenated blood from their air-breathing organ will mix with deoxygenated blood returning to the heart from the rest of the body. Lungfish, bichirs, ropefish, bowfins, snakefish, and the African knifefish have evolved to reduce such mixing, and to reduce oxygen loss from the gills to oxygen-poor water. Bichirs and lungfish have tetrapod-like paired lungs, requiring them to surface to gulp air, and making them obligate air breathers. Many other fish, including inhabitants ofrock poolsand theintertidal zone, are facultative air breathers, able to breathe air when out of water, as may occur daily atlow tide, and to use their gills when in water. Some coastal fish likerockskippersandmudskipperschoose to leave the water to feed in habitats temporarily exposed to the air.Some catfish  absorb air through their digestive tracts.
The digestive system consists of a tube, the gut, leading from the mouth to the anus. The mouth of most fishes contains teeth to grip prey, bite off or scrape plant material, or crush the food. Anesophaguscarries food to the stomach where it may be stored and partially digested. A sphincter, the pylorus, releases food to the intestine at intervals. Many fish have finger-shaped pouches,pyloric caeca, around the pylorus, of doubtful function. Thepancreassecretes enzymes into the intestine to digest the food; other enzymes are secreted directly by the intestine itself. Theliverproducesbilewhich helps to break up fat into an emulsion which can be absorbed in the intestine.
Most fish release their nitrogenous wastes asammonia. This may be excreted through the gills orfilteredby thekidneys. Salt is excreted by the rectal gland.Saltwater fish tend to lose water byosmosis; their kidneys return water to the body, and produce a concentrated urine. The reverse happens infreshwater fish: they tend to gain water osmotically, and produce a dilute urine. Some fish have kidneys able to operate in both freshwater and saltwater.
Fish have small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal.However, some fish have relatively large brains, notablymormyridsandsharks, which have brains about as large for their body weight as birds andmarsupials.At the front of the brain are theolfactory lobes, a pair of structures that receive and process signals from thenostrilsvia the twoolfactory nerves. Fish that hunt primarily by smell, such as hagfish and sharks, have very large olfactory lobes. Behind these is thetelencephalon, which in fish deals mostly with olfaction. Together these structures form the forebrain. Connecting the forebrain to the midbrain is thediencephalon; it works withhormonesandhomeostasis. Thepineal bodyis just above the diencephalon; it detects light, maintainscircadianrhythms, and controls color changes. Themidbraincontains the twooptic lobes. These are very large in species that hunt by sight, such asrainbow troutandcichlids. Thehindbraincontrols swimming and balance.The single-lobed cerebellum is the biggest part of the brain; it is small in hagfish andlampreys, but very large inmormyrids, processing theirelectrical sense. The brain stem ormyelencephaloncontrols some muscles and body organs, and governs respiration andosmoregulation.
Thelateral linesystem is a network of sensors in the skin which detects gentle currents and vibrations, and senses the motion of nearby fish, whether predators or prey.This can be considered both a sense oftouchand ofhearing.Blind cave fishnavigate almost entirely through the sensations from their lateral line system.Some fish, such as catfish and sharks, have theampullae of Lorenzini,electroreceptorsthat detect weak electric currents on the order of millivolt.
Visionis an importantsensory systemin fish.Fish eyes are similar to those ofterrestrialvertebrateslikebirdsand mammals, but have a moresphericallens.Theirretinasgenerally have bothrodsandcones(forscotopicandphotopic vision); many species havecolour vision, often with three types of cone.Teleosts can seepolarized light;some such as cyprinids have a fourth type of cone that detectsultraviolet.Amongstjawless fish, thelampreyhas well-developed eyes,while thehagfishhas only primitive eyespots.
Hearingtoo is an important sensory system in fish. Fish sense sound using their lateral lines andotolithsin their ears, inside their heads. Some can detect sound through the swim bladder.
Some fish, including salmon, are capable ofmagnetoreception; when the axis of a magnetic field is changed around a circular tank of young fish, they reorient themselves in line with the field.The mechanism of fish magnetoreception remains unknown;experiments in birds imply a quantumradical pair mechanism.
The cognitive capacities of fish includeself-awareness, as seen inmirror tests.Manta raysandwrassesplaced in front of a mirror repeatedly check whether their reflection's behavior mimics their body movement.Choerodonwrasse,archerfish, andAtlantic codcan solve problems and invent tools.ThemonogamouscichlidAmatitlania siquiaexhibits pessimistic behavior when prevented from being with its partner.Fish orient themselves using landmarks; they may use mental maps based on multiple landmarks. Fish are able to learn to traverse mazes, showing that they possess spatial memory and visual discrimination.Behavioral research suggests that fish aresentient, capable of experiencingpain.
Electric fishsuch aselephantfishes, theAfrican knifefish, andelectric eelshave some of their muscles adapted togenerate electric fields. They use the field to locate and identify objects such as prey in the waters around them, which may be turbid or dark.Strongly electric fish like the electric eel can in addition use theirelectric organsto generate shocks powerful enough to stun their prey.
Most fish are exclusively cold-blooded orectothermic. However, theScombroideiarewarm-blooded(endothermic), including thebillfishesand tunas.Theopah, alampriform, uses whole-body endothermy, generating heat with its swimming muscles to warm its body while countercurrent exchange minimizes heat loss.Among the cartilaginous fishes, sharks of the familiesLamnidae(such as the great white shark) andAlopiidae(thresher sharks) are endothermic. The degree of endothermy varies from the billfishes, which warm only their eyes and brain, to thebluefin tunaand theporbeagle shark, which maintain body temperatures more than 20 °C (68 °F) above the ambient water.
The primary reproductive organs are pairedtesticlesandovaries.Eggs are released from the ovary to theoviducts.Over 97% of fish, including salmon and goldfish, areoviparous, meaning that the eggs are shed into the water and develop outside the mother's body.The eggs are usually fertilized outside the mother's body, with the male and female fish shedding theirgametesinto the surrounding water. In a few oviparous fish, such as theskates, fertilization is internal: the male uses anintromittent organto deliver sperm into the female's genital opening of the female.Marine fish release large numbers of small eggs into the open water column. Newly hatched young of oviparous fish areplanktonic larvae. They have a largeyolk sacand do not resemble juvenile or adult fish. The larval period in oviparous fish is usually only some weeks, and larvae rapidly grow andchange in structureto become juveniles. During this transition, larvae must switch from their yolk sac to feeding onzooplanktonprey.Some fish such assurf-perches,splitfins, andlemon sharksareviviparousor live-bearing, meaning that the mother retains the eggs and nourishes the embryos via a structure analogous to theplacentato connect the mother's blood supply with the embryo's.
Embryos of externally fertilized fish species are directly exposed during their development to environmental conditions that maydamage their DNA, such as pollutants,UV lightandreactive oxygen species.To deal with such DNA damages, a variety of differentDNA repairpathways are employed by fish embryos during their development.In recent yearszebrafishhave become a useful model for assessing environmental pollutants that might be genotoxic, i.e. cause DNA damage.
Fish have both non-specific and immune defenses against disease. Non-specific defenses include the skin and scales, as well as the mucus layer secreted by theepidermisthat traps and inhibits the growth ofmicroorganisms. Ifpathogensbreach these defenses, theinnate immune systemcan mount aninflammatory responsethat increases blood flow to the infected region and deliverswhite blood cellsthat attempt to destroy pathogens, non-specifically. Specific defenses respond to particular antigens, such asproteinson the surfaces ofpathogenic bacteria, recognised by theadaptive immune system.Immune systems evolved indeuterostomesas shown in the cladogram.
Immune organs vary by type of fish. The jawless fish havelymphoid tissuewithin theanterior kidney, andgranulocytesin the gut. They havetheir own type of adaptive immune system; it makes use ofvariable lymphocyte receptors(VLR) to generate immunity to a wide range of antigens, The result is much like that of jawed fishes and tetrapods, but it may haveevolved separately.All jawed fishes have anadaptive immune systemwith B and TlymphocytesbearingimmunoglobulinsandT cell receptorsrespectively. This makes use ofVariable–Diversity–Joining rearrangement(V(D)J) to create immunity to a wide range of antigens. This system evolved once and is basal to the jawed vertebrate clade.Cartilaginous fish have three specialized organs that contain immune system cells: the epigonal organs around the gonads,Leydig's organwithin the esophagus, and aspiral valvein their intestine, while theirthymusandspleenhave similar functions to those of the same organs in the immune systems of tetrapods.Teleosts have lymphocytes in the thymus, and other immune cells in the spleen and other organs.
Ashoalis a loosely organised group where each fish swims and forages independently but is attracted to other members of the group and adjusts its behaviour, such as swimming speed, so that it remains close to the other members of the group. Aschoolis a much more tightly organised group, synchronising its swimming so that all fish move at the same speed and in the same direction.Schooling is sometimes anantipredator adaptation, offering improved vigilance against predators. It is often more efficient to gather food by working as a group, and individual fish optimise their strategies by choosing to join or leave a shoal. When a predator has been noticed, prey fish respond defensively, resulting in collective shoal behaviours such as synchronised movements. Responses do not consist only of attempting to hide or flee; antipredator tactics include for example scattering and reassembling. Fish also aggregate in shoals to spawn.Thecapelinmigrates annually in large schools between its feeding areas and its spawning grounds.
Fish communicate by transmitting acoustic signals (sounds) to each other. This is most often in the context of feeding, aggression or courtship.The sounds emitted vary with the species and stimulus involved. Fish can produce either stridulatory sounds by moving components of the skeletal system, or can produce non-stridulatory sounds by manipulating specialized organs such as the swimbladder.
Some fish produce sounds by rubbing or grinding their bones together. These sounds are stridulatory. InHaemulon flavolineatum, the French grunt fish, as it produces a grunting noise by grinding its teeth together, especially when in distress. The grunts are at a frequency of around 700 Hz, and last approximately 47 milliseconds.The longsnout seahorse,Hippocampus reidiproduces two categories of sounds, 'clicks' and 'growls', by rubbing their coronet bone across the grooved section of their neurocranium.Clicks are produced during courtship and feeding, and the frequencies of clicks were within the range of 50 Hz-800 Hz. The frequencies are at the higher end of the range during spawning, when the female and male fishes were less than fifteen centimeters apart. Growls are produced when theH. reidiare stressed. The 'growl' sounds consist of a series of sound pulses and are emitted simultaneously with body vibrations.
Some fish species create noise by engaging specialized muscles that contract and cause swimbladder vibrations.Oyster toadfishproduce loud grunts by contracting sonic muscles along the sides of the swim bladder.Female and male toadfishes emit short-duration grunts, often as a fright response.In addition to short-duration grunts, male toadfishes produce "boat whistle calls".These calls are longer in duration, lower in frequency, and are primarily used to attract mates.The various sounds have frequency range of 140 Hz to 260 Hz.The frequencies of the calls depend on the rate at which the sonic muscles contract.
The red drum,Sciaenops ocellatus, produces drumming sounds by vibrating its swimbladder. Vibrations are caused by the rapid contraction of sonic muscles that surround the dorsal aspect of the swimbladder. These vibrations result in repeated sounds with frequencies from 100 to >200 Hz.S. ocellatusproduces different calls depending on the stimuli involved, such as courtship or a predator's attack. Females do not produce sounds, and lack sound-producing (sonic) muscles.
The 2024IUCNRed Listnames 2,168 fish species that are endangered or critically endangered.Included are species such asAtlantic cod,Devil's Hole pupfish,coelacanths,andgreat white sharks.Because fish live underwater they are more difficult to study than terrestrial animals and plants, and information about fish populations is often lacking. However, freshwater fish seem particularly threatened because they often live in relatively small water bodies. For example, the Devil's Hole pupfish occupies only a single 3 by 6 metres (10 by 20 ft) pool.
TheFood and Agriculture Organizationreports that "in 2017, 34 percent of the fish stocks of the world's marine fisheries were classified as overfished".Overfishing is a major threat to edible fish such as cod andtuna.Overfishing eventually causesfish stocksto collapse, because the survivors cannot produce enough young to replace those removed. Such commercial extinction does not mean that the species is extinct, merely that it can no longer sustain a fishery. In the case of thePacific sardinefishery off the California coast, the catch steadily declined from a 1937 peak of 800,000 tonnes to an economically inviable 24,000 tonnes in 1968.In thecase of the Atlantic northwest cod fishery, overfishing reduced the fish population to 1% of its historical level by 1992.Fisheries scientistsand thefishing industryhave sharply differing views on the resiliency of fisheries to intensive fishing. In many coastal regions the fishing industry is a major employer, so governments are predisposed to support it.On the other hand, scientists and conservationists push for stringent protection, warning that many stocks could be destroyed within fifty years.
A key stress on both freshwater and marine ecosystems ishabitat degradationincludingwater pollution, the building of dams, removal of water for use by humans, and the introduction ofexoticspecies including predators.Freshwater fish, especially ifendemicto a region (occurring nowhere else), may be threatened with extinction for all these reasons, as is the case for three of Spain's ten endemic freshwater fishes.River dams, especially major schemes like theKariba Dam(Zambezi river) and theAswan Dam(River Nile) on rivers with economically important fisheries, have caused large reductions in fish catch.Industrial bottom trawlingcan damage seabed habitats, as has occurred on theGeorges Bankin the North Atlantic.Introduction of aquaticinvasive speciesis widespread. It modifies ecosystems, causing biodiversity loss, and can harm fisheries. Harmful species include fish but are not limited to them;the arrival of acomb jellyin the Black Sea damaged theanchovyfishery there.The opening of theSuez Canalin 1869 made possibleLessepsian migration, facilitating the arrival of hundreds of Indo-Pacific marine species of fish, algae and invertebrates in theMediterranean Sea, deeply impacting its overall biodiversityand ecology.The predatoryNile perchwas deliberately introduced toLake Victoriain the 1960s as a commercial and sports fish. The lake had high biodiversity, with some 500endemicspecies ofcichlidfish. It drastically altered the lake's ecology, andsimplified the fisheryfrom multi-species to just three: the Nile perch, thesilver cyprinid, and another introduced fish, theNile tilapia. Thehaplochrominecichlid populations have collapsed.
Throughout history, humans have usedfish as a food sourcefordietary protein. Historically and today, most fish harvested for human consumption has come by means of catching wild fish. However, fish farming, which has been practiced since about 3,500 BCE in ancient China,is becoming increasingly important in many nations. Overall, about one-sixth of the world's protein is estimated to be provided by fish.Fishingis accordingly a large global business which provides income for millions of people.TheEnvironmental Defense Fundhas a guide on which fish are safe to eat, given the state of pollution in today's world, and which fish are obtained in a sustainable way.As of 2020, over 65 million tonnes (Mt) of marine fish and 10 Mt of freshwater fish were captured, while some 50 Mt of fish, mainly freshwater, were farmed. Of the marine species captured in 2020,anchovetarepresented 4.9 Mt,Alaska pollock3.5 Mt,skipjack tuna2.8 Mt, andAtlantic herringandyellowfin tuna1.6 Mt each; eight more species had catches over 1 Mt.
Fish have been recognized as a source of beauty for almost as long as used for food, appearing incave art, being raised asornamental fishin ponds, and displayed inaquariumsin homes, offices, or public settings. Recreational fishing is fishing primarily for pleasure or competition; it can be contrasted with commercial fishing, which is fishing for profit, orartisanal fishing, which is fishing primarily for food. The most common form of recreational fishing employs arod,reel,line,hooks, and a wide range ofbaits. Recreational fishing is particularly popular in North America and Europe; government agencies often actively manage target fish species.
Fish themes have symbolic significance in many religions. In ancientMesopotamia, fish offerings were made to the gods from the very earliest times.Fish were also a major symbol ofEnki, the god of water.Fish frequently appear as filling motifs incylinder sealsfrom theOld Babylonian(c.1830 BC –c.1531 BC) andNeo-Assyrian(911–609 BC) periods.Starting during theKassite Period(c.1600 BC –c.1155 BC) and lasting until the earlyPersian Period(550–30 BC), healers and exorcists dressed in ritual garb resembling the bodies of fish.During theSeleucid Period(312–63 BC), the legendary Babylonianculture heroOanneswas said to have dressed in the skin of a fish.Fish were sacred to the Syrian goddessAtargatisand, during her festivals, only her priests were permitted to eat them.In theBook of Jonah, the central figure, aprophetnamedJonah, is swallowed by a giant fish after being thrown overboard by the crew of the ship he is travelling on.Early Christiansused theichthys, a symbol of a fish, to represent Jesus.Among thedeitiessaid to take the form of a fish areIkatereof thePolynesians,the shark-godKāmohoaliʻiofHawaiʻi,andMatsyaof the Hindus.The constellationPisces("The Fishes") is associated with a legend from Ancient Rome thatVenusand her sonCupidwere rescued by two fishes.
Fish feature prominently in art,in films such asFinding Nemoand books such asThe Old Man and the Sea.Large fish, particularly sharks, have frequently been the subject ofhorror moviesandthrillers, notably the novelJaws, made into a film which in turn has been parodied and imitated many times.Piranhas are shown in a similar light to sharks in films such asPiranha.