Notothenia is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of cod icefishes, ray-finned fish in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Nototheniidae

Nototheniidae

The cod icefishes or nothothens are the family Nototheniidae of acanthopterygian fishes, containing about 50 species in 13 genera. They are traditionally placed in the perciform assemblage together with their relatives, but like every lineage in the "Perciformes" their actual relationships are not...

. They inhabit the cold Southern Ocean

Southern Ocean

The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...

 and other waters around Antarctica. These fish have some adaptations that allow them to thrive in such inhospitable habitat

Habitat

* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

, like antifreeze protein

Antifreeze protein

Antifreeze proteins or ice structuring proteins refer to a class of polypeptides produced by certain vertebrates, plants, fungi and bacteria that permit their survival in subzero environments. AFPs bind to small ice crystals to inhibit growth and recrystallization of ice that would otherwise be...

s in their blood and ample fat to insulate them against heat loss and to offset their lack of a swim bladder.

Species

Many listings only feature 5 species: N. neglecta is often considered conspecific with N. coriiceps, while the little-known N. trigramma is of doubtful validity. Other species formerly placed herein are now in related genera like Lepidonotothen.

• Notothenia angustata – Maori chief
  Maori chief
  The Maori chief, Notothenia angustata, is a cod icefish in the genus Notothenia found in the southern ocean between New Zealand and Chile south to the Antarctic, at depths down to 100 m in rocky reef areas. Its length is between 30 and 65 cm....
  
  
• Notothenia coriiceps Richardson, 1844 – Black rockcod
• Notothenia cyanobrancha Richardson, 1844 – Blue rockcod
• Notothenia microlepidota – Black cod
  Black cod
  The black cod or smallscaled cod, Notothenia microlepidota, is a marine cod icefish in the genus Notothenia with distribution ranging from southern New Zealand to sub-Antarctic seas, although they have also been fished off the Great Australian Bight, Chile, and round the Falkland Islands, on rocky...
  
  , Small-scaled cod
• Notothenia neglecta Nybelin, 1951 – Yellowbelly rockcod
• Notothenia rossii – Marbled rockcod
  Marbled rockcod
  The marbled rockcod, Notothenia rossii, is a marine cod icefish in the family Nototheniidae with distribution ranging from southern New Zealand to sub-Antarctic seas, on rocky reefs...
  
  
• Notothenia trigramma Regan, 1913