: ''In some scientific literature, the term "cod icefish" is used to identify members of this family. This should not be confused with the term "icefish," which refers to the "white-blooded" fishes of the family

Channichthyidae The crocodile icefish or white-blooded fish comprise a family (Channichthyidae) of notothenioid fish found in the Southern Ocean around Antarctica. They are the only known vertebrates to lack hemoglobin in their blood as adults. Icefish populatio ...

. See Icefish (disambiguation).'' Nototheniidae, the notothens or cod icefishes, is a

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

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

es, part of the

suborder Order ( la, ordo) 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 ...

Notothenioidei Notothenioidei is one of 19 suborders of the order Perciformes. The group is found mainly in Antarctic and Subantarctic waters, with some species ranging north to southern Australia and southern South America. Notothenioids constitute approxima ...

which is traditionally placed within the order

Perciformes Perciformes (), also called the Percomorpha or Acanthopteri, is an order or superorder of ray-finned fish. If considered a single order, they are the most numerous order of vertebrates, containing about 41% of all bony fish. Perciformes means ...

. They are largely found in the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...

Taxonomy

Nototheniidae was described as a family in 1861 by the German-born British

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

Albert Günther with the

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...

being ''Notothenia'' which had been described in 1844 by Sir John Richardson with the species ''

Notothenia coriiceps ''Notothenia coriiceps'', also known as the black rockcod, Antarctic yellowbelly rockcod, or Antarctic bullhead notothen, is a species of marine ray-finned fish, belonging to the family Nototheniidae, the notothens or cod icefishes. It is widely ...

'' which Richardson had also described in 1844 subsequently being designated as the type in 1862 by

Theodore Nicholas Gill Theodore Nicholas Gill (March 21, 1837 – September 25, 1914) was an American ichthyologist, mammalogist, malacologist and librarian. Career Born and educated in New York City under private tutors, Gill early showed interest in natural history ...

. The name ''Notothenia'' means “coming from the south”, a reference to the Antarctic distribution of the genus. They are traditionally placed in the order

together with their relatives, Actual phylogenetic relationships among species of suborder

have not yet been determined with certainty.

Genera

The following subfamilies and genera are classified within the family Nototheniidae: * Pleuragrammatinae Andersen & Hureau 1979 ** '' Aethotaxis'' H. H. DeWitt, 1962 ** ''

Dissostichus ''Dissostichus'', the toothfish, is a genus of marine ray-finned fish belonging to the family Nototheniidae, the notothens or cod icefish. These fish are found in the Southern Hemisphere. Toothfish are marketed in the United States as Chilean ...

'' Smitt, 1898 ** '' Gvozdarus'' Balushkin, 1989 ** ''

Pleuragramma The Antarctic silverfish (''Pleuragramma antarctica''), or Antarctic herring, is a species of marine ray-finned fish belonging to the Family (biology), family Nototheniidae, the notothens or cod icefishes. It is native to the Southern Ocean and t ...

'' Balushkin, 1982 * Nototheniinae Günther 1861 ** ''

Gobionotothen ''Gobionotothen'' is a genus of marine ray-finned fishes belonging to the family Nototheniidae, the notothens or cod icefishes. They are native to the Southern Ocean. Taxonomy ''Gobionotothen'' was first formally described in 1976 by the Russian ...

'' Balushkin, 1976 ** '' Lepidonotothen'' Balushkin, 1976 ** ''

Lindbergichthys ''Lindbergichthys'' is a genus of marine ray-finned fishes belonging to the family Nototheniidae, the notothens or cod icefishes. Froese, R. and D. Pauly. Editors. (2021). FishBase. Lindbergichthys Balushkin, 1979. Accessed through: World Registe ...

'' Balushkin, 1979 ** ''

Notothenia ''Notothenia'' is a genus of marine ray-finned fishes belonging to the family Nototheniidae, the notothens or cod icefishes with the species in this genus often having the common name of rockcod. They are native to the Southern Ocean and other wa ...

Richardson Richardson may refer to: People * Richardson (surname), an English and Scottish surname * Richardson Gang, a London crime gang in the 1960s * Richardson Dilworth, Mayor of Philadelphia (1956-1962) Places Australia * Richardson, Australian Cap ...

, 1844 ** '' Nototheniops'' Balushkin, 1976 ** ''

Paranotothenia ''Paranotothenia'' is a genus of marine ray-finned fishes belonging to the family Nototheniidae, the notothens or cod icefishes. These fishes are native to the Southern Ocean. Taxonomy ''Paranotothenia'' was first formally described as a genus i ...

'' Balushkin, 1976 ** ''

Patagonotothen ''Patagonotothen'' is a genus of marine ray-finned fishes, belonging to the family Nototheniidae, the notothens or cod icefishes. They are native to the southeast Pacific Ocean, southern Atlantic Ocean and the Southern Ocean. Taxonomy ''Patagono ...

'' Balushkin, 1976 * Trematominae Balushkin,1982 ** ''

Cryothenia ''Cryothenia'' is a genus of marine ray-finned fishes, belonging to the family Nototheniidae, the notothens or cod icefishes. They are native to the Southern Ocean. Taxonomy ''Cryothenia'' was first formally described as a genus in 1981 by Rober ...

'' Daniels, 1981 ** ''

Pagothenia ''Pagothenia'' is a genus of marine ray-finned fishes, belonging to the family Nototheniidae, the notothens or cod icefishes. These fishes occur in the Southern Ocean. Taxonomy ''Pagothenia'' was formally described as a monotypic genus in 1936 b ...

Nichols Nichols may refer to: People *Nichols (surname) *Nichol, a surname Places Canada * Nichols Islands, Nunavut United States * Nichols, California, an unincorporated community * Nichols Canyon, Los Angeles, California * Nichols, Connecticut * Nich ...

& La Monte, 1936 ** ''

Trematomus ''Trematomus'' is a genus of marine ray-finned fishes, belonging to the Family (biology), family Nototheniidae, the notothens or cod icefishes. These fishes occur in the Southern Ocean. Taxonomy ''Trematomus'' was first described as a genus in 1 ...

'' Boulenger, 1902 These subfamilies are not recognised in the 5th Edition of ''

Fishes of the World ''Fishes of the World'' by the American ichthyologist Joseph S. Nelson (1937–2011) is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the ...

''.

Characteristics

Nototheniidae fishes have fusiform or elongate and oblong bodies. They typically have two

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s, the first having 3 to 11 spines and the second having 25-42 segmented fin rays. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is similar to the second dorsal fin and has 22 to 40 segmented rays. All but the last dorsal and anal fin rays are branched. The

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is rounded to forked and the

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s are large. The mouth is terminal and may be horizontal or angled with a protrusible upper jaw. There are no teeth on the roof of the mouth. in most species there are no spines on the preoperculum or operculum. Any scales are usually ctenoid although the spinules may be reduced or absent. They have between 1and 3

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

s. They vary in size from. Total length of in ''

Patagonotothen cornucola ''Patagonotothen'' is a genus of marine ray-finned fishes, belonging to the family Nototheniidae, the notothens or cod icefishes. They are native to the southeast Pacific Ocean, southern Atlantic Ocean and the Southern Ocean. Taxonomy ''Patagono ...

'' to in the

Patagonian toothfish The Patagonian toothfish (''Dissostichus eleginoides'') is a species of notothen found in cold waters () between depths of in the southern Atlantic, Pacific, and Indian Oceans and Southern Ocean on seamounts and continental shelves around most ...

(''Dissostichus eleginoides'').

Distribution and habitat

Nototheniidae species are largely found in the

and are particularly abundant off the shores of

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

. As the dominant Antarctic fish taxa, they occupy both sea-bottom and water-column ecological niches.

Biology

Nototheniidae species have no

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled Organ (anatomy), organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their curren ...

, however, they have other depth-related adaptations, such as increased fatty tissues and reduced mineralization of the bones, resulting in a body density approaching neutral, to fill a variety of niches. The spleen may be used to remove ice crystals from circulating blood. As the chilly Antarctica and sub-Antarctic waters of the Southern Ocean average , most species of these regions produce antifreeze glycoproteins to prevent the formation of ice crystals in blood and other body fluids. Some species exhibit polymorphism, for example, the circum-Antarctic ''

newnesi'' exists as two morphs in the

Ross Sea The Ross Sea is a deep bay of the Southern Ocean in Antarctica, between Victoria Land and Marie Byrd Land and within the Ross Embayment, and is the southernmost sea on Earth. It derives its name from the British explorer James Clark Ross who vi ...

, the typical morph and a large-mouthed/broad-headed morph.

Fisheries

Nototheniidae species are the major fish resource in the Southern Ocean, many notothens are under increasing pressure from

commercial fishing Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...

, particularly the

and the

Antarctic toothfish The Antarctic toothfish (''Dissostichus mawsoni'') is a large, black or brown fish found in very cold (subzero) waters of the Southern Ocean near Antarctica. It is the largest fish in the Southern Ocean, feeding on shrimp and smaller fish, and pr ...

References

{{Taxonbar, from=Q571462 Perciformes families Taxa named by Albert Günther