''Thymallus'' is a genus of

freshwater fish Freshwater fish are those that spend some or all of their lives in fresh water, such as rivers and lakes, with a salinity of less than 1.05%. These environments differ from marine conditions in many ways, especially the difference in levels of s ...

in the salmon family Salmonidae; it is the only genus of

subfamily 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 subfamily botanical names with "-oideae", and zoologi ...

Thymallinae. The type species is '' Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, but without qualification this also refers specifically to ''T. thymallus.''

Distribution

The fishes of this genus are native to the northern parts of the

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

and

Nearctic realm The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America t ...

s, ranging from the United Kingdom and northern Europe across Eurasia to Siberia, as well as northern

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. ''T. thymallus'', the grayling, is widespread in Europe, and ''T. arcticus,'' the Arctic grayling, is widespread throughout Eurasia east of the Ural Mountains and in the Nearctic. The other species have more localized ranges in northern Asia.

Appearance

''Thymallus'' species are distinguished from other members of the

salmon family Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

by their larger scales, their small mouths with teeth on the maxillary bone, and most striking of all, their showy, sail-like dorsal fins. This fin is longer in males and highly colourful, with spots of red, orange, purple or green. The body is also colourful; the dorsal surface is a dark purplish to bluish black or gray, grading to dark blue or silver gray on the flanks and gray or white on the belly. The body is further decorated with a smattering of small dark spots; these are much more numerous in juveniles. Grayling caught in the Colville River

The longest of the graylings is the Arctic grayling, ''T. arcticus'', at a maximum length of and a maximum weight of . ''T. thymallus,'' while somewhat shorter - - may weigh significantly more, . The fishes of this genus may live for 18 years or more.

Ecology and reproduction

These fishes require cool, well-oxygenated water, preferably with a swift current; they are found in large, sandy- or gravel-bottomed rivers and lakes, but ''T. thymallus'' may occasionally be found in brackish conditions. Generally omnivorous, they feed primarily on crustaceans, insects, and zooplankton. The grayling species, typically for salmonids, spawn in rivers and do not guard their brood, although they do conceal their eggs in silt. The spawning behavior of the Arctic grayling may be typical for the genus ''Thymallus''. As they are highly sensitive to changes in water quality, ''Thymallus'' fishes may be considered

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

; ''T. arcticus'' has largely disappeared from the Great Lakes Basin.

Human use

Due to their agreeable taste and attractive form, the grayling species are valued as food and game fishes, and they are occasionally seen in public aquaria. The most economically important of these fishes, for which

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...

and

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

operations exist, are the grayling (''T. thymallus'') and the Arctic grayling (''T. arcticus'').

Name

The name of the genus ''Thymallus'' first given to grayling (''T. thymallus'') described in the 1758 edition of ''Systema Naturae'' by Swedish zoologist Carl Linnaeus originates from the faint smell of the herb thyme, which emanates from the flesh. ''Thymallus'' derives from the Greek θύμαλλος, "thyme smell".

Species

According to

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

, 14 species are placed in this genus. However, views differ on their taxonomic rank. * '' Thymallus arcticus'' ( Pallas, 1776) - Arctic grayling * ''

Thymallus baicalensis ''Thymallus baicalensis'', also known as the Baikal black grayling, is a Siberian freshwater fish species in the salmon family Salmonidae. ''Thymallus baicalensis'' occurs in Lake Baikal, in the inflowing Selenga River and throughout the ma ...

'' Dybowski, 1874 - Baikal black grayling * ''

Thymallus brevipinnis ''Thymallus brevipinnis'' is a species of freshwater ray-finned fish belonging to the subfamily Thymallinae, the graylings, part of the family Salmonidae. This species is endemic to Lake Baikal in Siberia where it is benthopelagic. Some workers reg ...

'' Svetovidov ( ru), 1931 - Baikal white grayling * ''

Thymallus brevirostris ''Thymallus'' is a genus of freshwater fish in the salmon family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is '' Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, bu ...

Kessler Kessler or Keßler (in German) may refer to: * Kessler (automobile), an American automobile made 1921–1922 * Kessler (name), people named Kessler * ''Kessler'' (TV series), a British television series from 1981 * Kessler, Ohio, an unincorporat ...

, 1879 - Mongolian grayling * ''

Thymallus burejensis ''Thymallus'' is a genus of freshwater fish in the salmon family (biology), family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is ''Thymallus thymallus,'' the grayling. The species in the genus are generically call ...

'' Antonov, 2004 * ''

Thymallus flavomaculatus ''Thymallus'' is a genus of freshwater fish in the salmon family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is ''Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, but ...

'' Knizhin, Antonov & Weiss, 2006 - yellow-spotted grayling * ''

Thymallus grubii ''Thymallus'' is a genus of freshwater fish in the salmon family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is ''Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, but ...

'' Dybowski, 1869 - Amur grayling *''

Thymallus mertensii The Kamchatka grayling (''Thymallus mertensii'') is a grayling in the salmon family Salmonidae. The fish grows up to . It is found in freshwater habitats of the Russian Far East, including the Kamchatka Peninsula, eastern part of Magadan Oblast ...

'' Valenciennes, 1848 * ''

Thymallus nigrescens ''Thymallus'' is a genus of freshwater fish in the salmon family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is ''Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, but ...

'' Dorogostaisky, 1923 - Kosogol grayling * '' Thymallus pallasii'' Valenciennes, 1848 - East Siberian grayling * ''

Thymallus svetovidovi ''Thymallus svetovidovi'', also known as the Upper Yenisei grayling, is a species of freshwater fish in the salmon family. It is found in the upper reaches of the Yenisei River and in western Mongolia. Description The body of Upper Yenisei grayl ...

'' Knizhin & Weiss, 2009 - Upper Yenisei grayling * '' Thymallus thymallus'' ( Linnaeus,

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, 10th edition of ''Systema Naturae'', the sta ...

) - grayling * ''

Thymallus tugarinae ''Thymallus tugarinae'', also known as the Lower Amur grayling, is a species of freshwater fish in the salmon family. It is found in the lower reaches of the Amur river on the border of the Russian far east and Heilongjiang Province of China. It ...

'' Knizhin, Antonov, Safronov & Weiss, 2007 - Lower Amur grayling * ''

Thymallus yaluensis ''Thymallus yaluensis'' is a putative species of freshwater fish, a grayling in the salmon family Salmonidae. It is endemic to the upper Yalu River in Korea, on the Chinese border. ''Thymallus yaluensis'' is a small fish, the maximum recorded le ...

'' T. Mori, 1928 Modern reviewsWeiss, S. J., D. V. Gonçalves, G. Secci-Petretto, G. K. Englmaier, A. Gomes-Dos-Santos, G. P. J. Denys, H. Persat, A. Antonov, C. Hahn, E. B. Taylor and E. Froufe (2021) Global systematic diversity, range distributions, conservation and taxonomic assessments of graylings (Teleostei: Salmonidae; ''Thymallus'' spp.). ''Organisms Diversity & Evolution'': -18 (published online 25 Nov. 2020) and the '' Catalog of Fishes'' also list additional species including ''

Thymallus nikolskyi ''Thymallus'' is a genus of freshwater fish in the salmon family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is ''Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, but ...

'' , ''

Thymallus baicalolenensis ''Thymallus'' is a genus of freshwater fish in the salmon family Salmonidae; it is the only genus of subfamily Thymallinae. The type species is ''Thymallus thymallus,'' the grayling. The species in the genus are generically called graylings, but ...

'' and ''

Thymallus ligericus ''Thymallus ligericus'', the Loire grayling, is a European freshwater fish species in the salmon family Salmonidae. The species is endemic to the upper Loire drainage in France, where it lives in medium to large foothill, canyon and plateau riv ...

'' . An old controversy exists over the status of Baikal black vs white graylings, ''T. baicalensis'' and ''T. brevipinnis''. Modern research supports the view that they are not separate taxa, but alternative ecological forms of ''T. baicalensis''.Knizhin IB, Weiss SJ, Sushnik S (2006) Graylings of Baikal lake basin (''Thymallus'', Thymallidae): Diversity of forms and their taxonomic status. ''Journal of Ichthyology'' 46, 418-435.

References

{{Authority control Extant Pleistocene first appearances Ray-finned fish genera Holarctic fauna