Mackerel Icefish

The mackerel icefish has a long, spindle-shaped body with whitish gills and a bluish-silver color. It has an elongated snout and a large mouth with small teeth. The dorsal fins are black in adults and the second caudal fins and anal fins of adult males have distinctive white margins. The mackerel icefish can grow to 66 cm (26 in) in standard length, but is more commonly about 35 cm (14 in) TL. It has a maximum published weight of 2.0 kg (4.4 lb). This species is markedly smaller in the Kerguelen Islands, where they only reach 45 cm (17 inches) TL.

This species has a maximum lifespan of 15 years and eats krill (making up more than 95% of the diet in more southerly areas) and mysids. Myctophids are also taken, at least in South Georgia and the Kerguelen Islands.They are in turn preyed on by seabirds, seals and other notothens. This species practices daily vertical migration and is a schooling species. This species, which becomes reproductively mature at 3–4 years old, is a synchronous spawner and spawns in the Southern Hemisphere autumn and winter. Sexually mature males have a significantly higher dorsal fin than females. This species moves inshore to spawn. Females produce 10 000 to 20 000 large eggs that remain on the seabed for about 3 months before hatching. Hatching takes place from August to October in South Georgia and in October around the Kerguelen Islands. The larvae have a long pelagic phase.