''Thymallus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

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 ...

in the salmon

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Salmonidae Salmonidae is a family of ray-finned fish that constitutes the only currently extant family in the order Salmoniformes . It includes salmon (both Atlantic and Pacific species), trout (both ocean-going and landlocked), chars, freshwater whitefis ...

; it is the only genus of subfamily Thymallinae. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is ''

Thymallus thymallus ''Thymallus thymallus'', the grayling or European grayling, is a species of freshwater fish in the salmon family Salmonidae. It is the only species of the genus ''Thymallus'' (the graylings) native to Europe, where it is widespread from the Unit ...

,'' 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 and Nearctic realms, ranging from the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

and northern

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...

across Eurasia to Siberia, as well as northern North America. ''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 salmonidae, salmon family 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 Salmonidae, 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; ''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 fishery, fisheries and aquaculture 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 10th edition of Systema Naturae, 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 language, Greek θύμαλλος, "thyme smell".

Species

According to FishBase, 14 species are placed in this genus. However, views differ on their taxonomic rank. * ''Thymallus arcticus'' (Peter Simon Pallas, Pallas, 1776) - Arctic grayling * ''Thymallus baicalensis'' Benedykt Dybowski, Dybowski, 1874 - Baikal black grayling * ''Thymallus brevipinnis'' Anatolii Nikolaevich Svetovidov, Svetovidov (:ru:Световидов, Анатолий Николаевич, ru), 1931 - Baikal white grayling * ''Thymallus brevirostris'' Karl Fedorovich Kessler, Kessler, 1879 - Mongolian grayling * ''Thymallus burejensis'' Alexander Leonidovich Antonov, Antonov, 2004 * ''Thymallus flavomaculatus'' Igor Borisovich Knizhin, Knizhin, Alexander Leonidovich Antonov, Antonov & Steven J. Weiss, Weiss, 2006 - yellow-spotted grayling * ''Thymallus grubii'' Benedykt Dybowski, Dybowski, 1869 - Amur grayling *''Thymallus mertensii'' Achille Valenciennes, Valenciennes, 1848 * ''Thymallus nigrescens'' Vitaly Cheslavovich Dorogostaisky, Dorogostaisky, 1923 - Kosogol grayling * ''Thymallus pallasii'' Valenciennes, 1848 - East Siberian grayling * ''Thymallus svetovidovi'' Igor Borisovich Knizhin, Knizhin & Steven J. Weiss, Weiss, 2009 - Upper Yenisei grayling * ''

'' (Carl Linnaeus, Linnaeus, 10th edition of Systema Naturae, 1758) - grayling * ''Thymallus tugarinae'' Knizhin, Antonov, Safronov & Weiss, 2007 - Lower Amur grayling * ''Thymallus yaluensis'' Tamezo Mori, 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'': [1-18]. (published online 25 Nov. 2020) and the ''Catalog of Fishes'' also list additional species including ''Thymallus nikolskyi'' , ''Thymallus baicalolenensis'' and ''Thymallus ligericus'' . 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 Thymallus, Extant Pleistocene first appearances Ray-finned fish genera Holarctic fauna