Salmonidae (, ) is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, the only extant member of the

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Salmonoidei, consisting of 11 extant

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

and over 200

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

collectively known as "salmonids" or "salmonoids". The family includes

salmon Salmon (; : salmon) are any of several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the genera ''Salmo'' and ''Oncorhynchus'' of the family (biology), family Salmonidae, native ...

(both Atlantic and Pacific species),

trout Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

(both ocean-going and landlocked), char, graylings,

freshwater whitefish The freshwater whitefish are fishes of the subfamily Coregoninae, which contains whitefishes (both freshwater and anadromous) and ciscoes, and is one of three subfamilies in the salmon family Salmonidae. Apart from the subfamily Coregoninae, ...

es,

taimen ''Hucho'' is a genus of large piscivorous salmonid fish known as taimens (from Finnish , 'trout', through ), and is closely related to Pacific trout and lenoks (all belonging to the same tribe in the subfamily Salmoninae). Native to the cold ...

s and

lenok Lenoks, otherwise known as Asiatic trout or Manchurian trout,James Card: Fly fishing in South Korea.' Retrieved 22 June 2015. are salmonid fish of the genus ''Brachymystax'', native to rivers and lakes in Mongolia, Kazakhstan, wider Siberia (incl ...

s, all coldwater mid-

level Level or levels may refer to: Engineering *Level (optical instrument), a device used to measure true horizontal or relative heights * Spirit level or bubble level, an instrument designed to indicate whether a surface is horizontal or vertical *C ...

predatory fish Predatory fish are hypercarnivorous fish that actively prey upon other fish or aquatic animals, with examples including shark, billfish, barracuda, alligator gar, tuna, dolphinfish, walleye, perch and salmon. Some omnivorous fish, such as t ...

that inhabit the

subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of hemiboreal regions and covering much of Alaska, Canada, Iceland, the north of Fennoscandia, Northwestern Russia, Siberia, and the Cair ...

and cool

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

waters of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

. The

Atlantic salmon The Atlantic salmon (''Salmo salar'') is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Hucho taimen, Siberian taimen and Pacific Chinook salmon, growing up to a meter in length. Atlan ...

(''Salmo salar''), whose

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

name became that of its

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Salmo ''Salmo'' is a genus of ray-finned fish from the subfamily Salmoninae of family (biology), family Salmonidae, and is part of the tribe (biology), tribe Salmonini along with the sister genera ''Salvelinus'' and ''Salvethymus''. Almost all ''Salmo ...

'', is also the

eponym An eponym is a noun after which or for which someone or something is, or is believed to be, named. Adjectives derived from the word ''eponym'' include ''eponymous'' and ''eponymic''. Eponyms are commonly used for time periods, places, innovati ...

of the family and order names. Salmonids have a relatively primitive appearance among

teleost Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

fish, with the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s being placed far back, and an

adipose fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only b ...

towards the rear of the back. They have slender bodies with rounded scales and forked tail fins, and their

mouth A mouth also referred to as the oral is the body orifice through which many animals ingest food and animal communication#Auditory, vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also t ...

s contain a single row of sharp

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

. Although the smallest salmonid species is just long for adults, most salmonids are much larger, with the largest reaching . All salmonids are

migratory fish Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousa ...

that

spawn Spawn or spawning may refer to: * Spawning, the eggs and sperm of aquatic animals Arts, entertainment and media * Spawn (character), a fictional character in the comic series of the same name and in the associated franchise ** ''Spawn: Armageddon' ...

in the shallow

gravel Gravel () is a loose aggregation of rock fragments. Gravel occurs naturally on Earth as a result of sedimentation, sedimentary and erosion, erosive geological processes; it is also produced in large quantities commercially as crushed stone. Gr ...

bed A bed is a piece of furniture that is used as a place to sleep, rest, and relax. Most modern beds consist of a soft, cushioned mattress on a bed frame. The mattress rests either on a solid base, often wood slats, or a sprung base. Many beds ...

s of

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

headstream The headwater of a river or stream is the geographical point of its beginning, specifically where surface runoff water begins to accumulate into a flowing channel of water. A river or stream into which one or many tributary rivers or streams flo ...

s, spend the growing juvenile years in

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s, creeks, small

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s and

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

s, but migrate downstream upon maturity and spend most of their

adult An adult is an animal that has reached full growth. The biological definition of the word means an animal reaching sexual maturity and thus capable of reproduction. In the human context, the term ''adult'' has meanings associated with social an ...

lives at much larger waterbodies. Many salmonid species are

euryhaline Euryhaline organisms are able to adapt to a wide range of salinities. An example of a euryhaline fish is the short-finned molly, '' Poecilia sphenops'', which can live in fresh water, brackish water, or salt water. The green crab ('' Carcinus m ...

and migrate to the

sea A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

as soon as they approach adulthood, returning to the upper streams only to reproduce. Such sea-run life cycle is described as ''

anadromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousa ...

'', and other freshwater salmonids that migrate purely between lakes and rivers are considered ''

potamodromous Fish migration is animal migration, mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few ...

''. Salmonids are

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s of the middle

food chain A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as ...

, feeding on smaller fish,

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

aquatic insect Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some ''diving'' insects, such as predatory diving beetles, can hunt for food underwater where land-living insects ...

s and

larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...

tadpole A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...

s and sometimes

fish egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...

s (even those of their own kind), and in turn being preyed upon by larger predators. Many species of salmonids are thus considered keystone organisms important for both

and

terrestrial ecosystem Terrestrial ecosystems are ecosystems that are found on land. Examples include tundra, taiga, temperate deciduous forest, tropical rain forest, grassland, deserts. Terrestrial ecosystems differ from aquatic ecosystems by the predominant presen ...

s due to the

biomass Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how ...

transfer provided by their mass migration from oceanic to inland waterbodies.

Evolution

Current salmonids comprise three main

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

s taxonomically treated as

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zool ...

: Coregoninae (

es), Thymallinae ( graylings), and

Salmoninae Salmonidae (, ) is a family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmon (both Atlantic a ...

(

, char, taimens and

s). Generally, all three lineages are accepted to allocate a suite of derived traits indicating a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group. The suborder Salmonoidei, containing only Salmonidae, is one of two extant clades within the order Salmoniformes, which first appeared during the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

and

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

stages of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

. The other is the

Esocoidei The Esocoidei () is a small suborder of freshwater ray-finned fish, one of two suborders in the order Salmoniformes. It contains two families, Umbridae and Esocidae. The pikes of genus ''Esox'' give the order its name. This order is closely rel ...

, which contains the pikes and mudminnows. Formerly, many more families were included within this group, but all have since been reclassified into their own orders. During the early 21st century, Salmoniformes was redefined to include only Salmonidae as a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

order. However, as recent phylogenetic studies have affirmed the relationship between the Salmonoidei and Esocoidei, the latter have returned to being considered a suborder of Salmoniformes. Eosalmo driftwoodensis 02

It is thought that salmon and pike diverged from one another during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

, but until 2025, there was no

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

evidence of salmonids occurring during this time period. In 2025, the earliest known fossil salmonid, '' Sivulliusalmo alaskensis'', was described from the early

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

-aged

Prince Creek Formation The Prince Creek Formation is a geological Formation (geology), formation in Alaska with strata dating to the Late Campanian stage of the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.Weishamp ...

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

, with indeterminate remains of this genus also being identified from the older

-aged

Dinosaur Park Formation The Dinosaur Park Formation is the uppermost member of the Belly River Group (also known as the Judith River Group), a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 7 ...

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

. The occurrence of ''Sivulliusalmo'' in these northern habitats suggests that the modern salmonid preference for cool, high-latitude waters is an ancient, conserved trait. Prior to the description of ''Sivulliusalmo'', the earliest record of salmonids was the

Early Eocene In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

-aged ''Eosalmo driftwoodensis'', a stem- salmonine, which was first described from fossils found at Driftwood Creek, central

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

, and has been recovered from most sites in the

Eocene Okanagan Highlands The Eocene Okanagan Highlands or Eocene Okanogan Highlands are a series of Early Eocene geological formations which span a transect of British Columbia, Canada, and Washington state, United States. Known for a highly diverse and detailed plant ...

.Wilson, M.V.H. 2009. McAbee Fossil Site Assessment Report. 60 p
Online PDF
Accessed 17 May 2021. This genus shares traits found in all three subfamily lineages. Hence, ''E. driftwoodensis'' is an archaic salmonid, representing an important stage in salmonid evolution. Fossil scales of coregonines are known from the Late Eocene or Early Oligocene of California. A gap appears in the salmonine fossil record after ''E. driftwoodensis'' until about 7 million years ago ( mya), in the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

, when trout-like fossils appear in

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

, in the Clarkia Lake beds. Several of these species appear to be ''

Oncorhynchus ''Oncorhynchus'', from Ancient Greek ὄγκος (''ónkos''), meaning "bend", and ῥύγχος (''rhúnkhos''), meaning "snout", is a genus of ray-finned fish in the subfamily Salmoninae of the family (biology), family Salmonidae, native to col ...

'' — the current genus for Pacific salmon and Pacific trout. The presence of these species so far inland established that ''Oncorhynchus'' was not only present in the Pacific drainages before the beginning of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58rainbow A rainbow is an optical phenomenon caused by refraction, internal reflection and dispersion of light in water droplets resulting in a continuous spectrum of light appearing in the sky. The rainbow takes the form of a multicoloured circular ...

and

cutthroat trout The cutthroat trout (''Oncorhynchus clarkii'' clade) is a clade of four fish species of the Family (biology), family Salmonidae native to cold-water Tributary, tributaries of the Pacific Ocean, Rocky Mountains, and Great Basin in North America. ...

, and Pacific salmon lineages had diverged before the beginning of the Pliocene. Consequently, the split between ''Oncorhynchus'' and ''

'' (Atlantic salmon and European trout) must have occurred well before the Pliocene. Suggestions have gone back as far as the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

(about 20 mya).

Genetics

Based on the most current evidence, salmonids diverged from the rest of

teleost fish Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

no later than 88 million years ago, during the late

. This divergence was marked by a whole-genome duplication event in the ancestral salmonid, where the diploid ancestor became

tetraploid Polyploidy is a condition in which the cells of an organism have more than two paired sets of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one fro ...

. This duplication is the fourth of its kind to happen in the evolutionary lineage of the salmonids, with two having occurred commonly to all bony vertebrates, and another specifically in the teleost fishes. Extant salmonids all show evidence of partial tetraploidy, as studies show the genome has undergone selection to regain a diploid state. Work done in the

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

(''Onchorhynchus mykiss'') has shown that the genome is still partially-tetraploid. Around half of the duplicated protein-coding genes have been deleted, but all apparent miRNA sequences still show full duplication, with potential to influence regulation of the rainbow trout's genome. This pattern of partial tetraploidy is thought to be reflected in the rest of extant salmonids. The earliest presumed

crown-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

salmonid fish ('' E. driftwoodensis'') does not appear until the middle Eocene. This fossil already displays traits associated with extant salmonids, but as the genome of E. ''driftwoodensis'' cannot be sequenced, it cannot be confirmed if polyploidy was present in this animal at this point in time. Given a lack of earlier transition fossils, and the inability to extract genomic data from specimens other than extant species, the dating of the whole-genome duplication event in salmonids was historically a very broad categorization of times, ranging from 25 to 100 million years in age. New advances in calibrated relaxed molecular clock analyses have allowed for a closer examination of the salmonid genome, and has allowed for a more precise dating of the whole-genome duplication of the group, that places the latest possible date for the event at 88 million years ago. This more precise dating and examination of the salmonid whole-genome duplication event has allowed more speculation on the radiation of species within the group. Historically, the whole-genome duplication event was thought to be the reason for the variation within Salmonidae. Current evidence done with molecular clock analyses revealed that much of the speciation of the group occurred during periods of intense climate change associated with the last ice ages, with especially high speciation rates being observed in salmonids that developed an anadromous lifestyle.

Classification

Together with the closely related orders

Esociformes The Esocoidei () is a small suborder of freshwater Actinopterygii, ray-finned fish, one of two suborders in the order Salmoniformes. It contains two families, Umbridae and Esocidae. The pikes of genus ''Esox'' give the order its name. This order ...

(

pike Pike, Pikes or The Pike may refer to: Fish * Blue pike or blue walleye, an extinct color morph of the yellow walleye ''Sander vitreus'' * Ctenoluciidae, the "pike characins", some species of which are commonly known as pikes * ''Esox'', genus of ...

s and mudminnows),

Osmeriformes The Osmeriformes are an order (biology), order of ray-finned fish that includes the true or freshwater smelts and allies, such as the noodlefishes; they are also collectively called osmeriforms. They belong to the teleost superorder Protacanthopt ...

( true smelts) and

Argentiniformes The Argentiniformes is an order of marine ray-finned fish whose distinctness was recognized only fairly recently. In former times, they were included in the Osmeriformes (typical smelt and allies) as suborder Argentinoidei. That term refers onl ...

(

marine smelt The Argentiniformes is an order of marine ray-finned fish whose distinctness was recognized only fairly recently. In former times, they were included in the Osmeriformes (typical smelt and allies) as suborder Argentinoidei. That term refers on ...

s and

barreleye Barreleyes, also known as spook fish (a name also applied to several species of chimaera (fish), chimaera), are small deep-sea Argentiniformes, argentiniform fish comprising the family (biology), family Opisthoproctidae found in tropical-to-temp ...

s), Salmoniformes comprise the

superorder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Protacanthopterygii Protacanthopterygii is a superorder of ray-finned fish. They inhabit both Marine (ocean), marine and freshwater habitats. They appear to have evolved in the Cretaceous or perhaps late Jurassic, originating probably roughly 150 million years ago; ...

. The only extant family within Salmoniformes, Salmonidae, is divided into three

and around 10

containing about 220

. The concepts of the number of species recognised vary among researchers and authorities; the numbers presented below represent the higher estimates of diversity: Order Salmoniformes * Family: Salmonidae ** †'' Sivulliusalmo'' Brinkman ''et al''., 2025 (1 species,

) ** Subfamily: Coregoninae *** ''

Coregonus ''Coregonus'' is a diverse genus of fish in the salmon family (Salmonidae). The ''Coregonus'' species are known as whitefishes. The genus contains at least 68 described extant taxa, but the true number of species is a matter of debate. The type ...

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of ''Systema Naturae'', the starting point of modern zoologic ...

- whitefishes (78 species) *** ''

Prosopium ''Prosopium'' is a genus of freshwater whitefishes found in North America and parts of eastern Russia. It contains three fairly widespread species: the round whitefish, the pygmy whitefish, and the mountain whitefish. The remaining species, the B ...

Jordan Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...

, 1878 - round whitefishes (6 species) *** ''

Stenodus ''Stenodus'' is a genus of large-sized whitefish in the family Salmonidae. It consists of two species; one of them ( beloribitsa) is extinct in the wild. The two species have alternatively been considered subspecies of the single species ''Steno ...

'' Richardson, 1836 -

beloribitsa ''Stenodus leucichthys'', also known as the inconnu, sheefish, ''ak balyk'', or ''beloribitsa'', is a species of large, anadromous, freshwater whitefish in the family Salmonidae. In the strict sense its natural distribution is restricted to the ...

and

nelma ''Stenodus nelma'', known alternatively as the nelma, sheefish, siifish, inconnu or connie, is a commercial species of freshwater whitefish in the family Salmonidae. It is widespread in the Arctic rivers from the Kola Peninsula (White Sea basin) ...

(2 species) *** †''

Beckius ''Beckius'' is an extinct genus of marine whitefish known from the Early Oligocene of California. It contains a single species, ''B. plicatus'', known only from a single fossilized scale from the Tumey Formation, a lens of the Kreyenhagen Shal ...

'' David, 1946 (1 species,

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

) *** †'' Parastenodus'' David, 1946 (1 species,

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

) ** Subfamily: Thymallinae *** ''

Thymallus ''Thymallus'', commonly known as graylings, is a genus of freshwater ray-finned fish and the only genus within the subfamily Thymallinae of the family Salmonidae. Although all ''Thymallus'' species can be generically called graylings, withou ...

'' Linck, 1790 - graylings (14 species) ** Subfamily: Salmoninae ***

† A dagger, obelisk, or obelus is a typographical mark that usually indicates a footnote if an asterisk has already been used. The symbol is also used to indicate death (of people) or extinction (of species or languages). It is one of the mo ...

Eosalmo ''Eosalmo'' is an extinct genus of ancient freshwater salmonid with a single described species ''Eosalmo driftwoodensis''. The genus lived during the Eocene epoch and has been recovered from late Ypresian fossils in the Eocene Okanagan Highlands ...

'' Wilson, 1977 (1 species, Eocene) *** †'' Paleolox'' Kimmel, 1975 (1 species,

) ***

Tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

: Salmonini **** ''

'' Linnaeus, 1758 -

and

(47 species) **** ''

Salvelinus ''Salvelinus'' is a genus of Salmonidae, salmonid fish often called char or charr; some species are called "trout". ''Salvelinus'' is a member of the subfamily Salmoninae within the family Salmonidae. The genus has a northern circumpolar distrib ...

'' Richardson, 1836 - Char and trout (e.g.

brook trout The brook trout (''Salvelinus fontinalis'') is a species of freshwater fish in the char genus ''Salvelinus'' of the salmon family Salmonidae native to Eastern North America in the United States and Canada. Two ecological forms of brook trout h ...

lake trout The lake trout (''Salvelinus namaycush'') is a freshwater Salvelinus, char living mainly in lakes in Northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, laker, and grey trout. In Lake Sup ...

) (51 species) **** ''

Salvethymus ''Salvethymus svetovidovi'', also called the long-finned charr, is a species of salmonid fish. It is endemic to Elgygytgyn Lake in Chukotka, Far East of Russia, together with two other species, the small-mouth char ''Salvelinus elgyticus'', and ...

'' Chereshnev & Skopets, 1990 - Long-finned char (1 species) *** Tribe: Oncorhynchini **** '' Brachymystax'' Günther, 1866 -

s (4 species) **** ''

Hucho ''Hucho'' is a genus of large piscivorous salmonid fish known as taimens (from Finnish , 'trout', through ), and is closely related to Pacific trout and lenoks (all belonging to the same tribe in the subfamily Salmoninae). Native to the cold ri ...

'' Günther, 1866 -

s (4 species) **** ''

Suckley Suckley is a village and civil parish in the Malvern Hills District in the county of Worcestershire, England, close to the border with Herefordshire. The parish includes the hamlets of Suckley Knowl (at ), Suckley Green at and Longley Green a ...

, 1861 - Pacific salmon and trout (12 species) **** '' Parahucho'' Vladykov, 1963 - Sakhalin taimen (1 species)

Hybrid crossbreeding

The following table shows results of hybrid crossbreeding combination in Salmonidae. note :- : The identical kind, O : (survivability), X : (Fatality)

Evolution

Genetics

Classification

Hybrid crossbreeding

References

Further reading