What is "notothenioidei"

Notothenioidei is one of 18 suborders from the order Perciformes and includes Antarctic fish and sub-Antarctic fish. Notothenioids are distributed mainly throughout the Southern Ocean around the coasts of New Zealand, South America, and Antarctica. The main seawater temperatures between −2 and 4 °C (28 and 39 °F), but some the subpolar species inhabit waters that may be as warm as 10 °C (50 °F) around New Zealand and South America. Seawater temperatures below the freezing point of fresh water (0 °C or 32 °F) are possible due to the dissolved salts.

Notothenioids have a depth range of about 0–1,500 m (0–4,921 ft).

Comparison studies between sub-Antarctic and Antarctic notothenioids have revealed different ecological processes and genetic differences between the two groups of fish, like loss of hemoglobin and changes in buoyancy.