Antarctic toothfish
A large, antifreeze-equipped fish of the Southern Ocean, marketed as Chilean sea bass.
The Antarctic toothfish is a large bony fish found in the icy waters near Antarctica. It is the largest species in its ocean region and feeds on smaller fish and crustaceans while serving as prey for whales and seals.
- Largest bony fish in the Southern Ocean, reaching 1.7m and 135kg.
- Produces antifreeze glycoproteins to survive subzero water temperatures.
- Marketed globally as Chilean sea bass alongside the Patagonian toothfish.
- Managed by CCAMLR since 1997 with strict ecosystem-based rules.
- Reaches sexual maturity late, taking 13 to 17 years to spawn.
What it is
The Antarctic toothfish is a large, dark-colored fish inhabiting the freezing seas around Antarctica. Adults can exceed 1.7 meters in length and weigh over 135 kilograms, making them the biggest bony fish in that region. Their bodies are black or olive brown with lighter undersides, helping them blend into deep sponges and corals. They possess a broad head, elongated shape, and long fins. Unlike many bottom-dwellers, adults achieve neutral buoyancy through fatty deposits, allowing them to swim freely in mid-water without expending extra energy.
Where it lives
This species lives in subzero waters south of latitude 60°S. It is found across the Southern Ocean, including the Ross Sea, areas near the Antarctic Peninsula, and waters around the South Sandwich Islands. While they can dive to depths of 2200 meters, most occur on continental slopes and shelves. The fish thrives in these extreme conditions due to special proteins that prevent ice crystals from forming in their blood, a trait absent in their warmer-water relatives.
How it lives
Antarctic toothfish are voracious predators that feed on shrimp, silverfish, grenadiers, skates, and colossal squid. They use excellent vision and smell to hunt in low-light environments under ice. As apex predators in their zone, they fill an ecological role similar to sharks elsewhere. Large adults are hunted by sperm whales, killer whales, and Weddell seals. Younger fish stay in shallower waters to avoid being eaten by larger members of their own species.
Breeding and life cycle
These fish grow quickly when young but slow down significantly after ten years, reaching maturity between thirteen and seventeen years old. Spawning occurs during the winter months, often near seamounts on the Pacific-Antarctic Ridge. Females produce large eggs, though exact fecundity remains unknown due to limited observations. After spawning, adults may become depleted of fat reserves before returning to deeper slope waters to recover.
Fish and people
The species is caught commercially and sold as Chilean sea bass alongside the Patagonian toothfish. Fishing began in 1997 under CCAMLR management, primarily in the Ross Sea. The practice is controversial due to concerns about ecosystem impacts and data gaps regarding population sizes. Bycatch of other species is regulated, and mitigation measures aim to protect seabirds. Research programs monitor subadult populations to ensure sustainable harvest levels and understand ecosystem dynamics.
Status and threats
Conservation status is listed as data deficient because key parameters like original stock size and recruitment rates are poorly understood. Management targets maintain spawning biomass above 50% of pre-exploitation levels to protect dependent predators. Some studies suggest declines in large fish numbers or shifts in predator behavior, such as killer whale migration patterns. Ongoing surveys provide early warnings of changes in recruitment variability to guide future management decisions.
Questions people ask about Antarctic toothfish
What is the scientific name of the Antarctic toothfish?
The scientific name is Dissostichus mawsoni. It was first formally described by John Roxborough Norman in 1937. The genus name refers to two lateral lines, and the species name honors geologist Douglas Mawson.
How does the Antarctic toothfish survive freezing water?
It produces antifreeze glycoproteins that prevent ice crystals from forming in its body fluids. This adaptation allows it to thrive in subzero temperatures where its closest relative, the Patagonian toothfish, cannot survive.
Why is the fishing of this species controversial?
Critics argue there is insufficient data on population size, fecundity, and recruitment. Concerns also exist about the impact on the ecosystem, particularly regarding predators like whales and seals that rely on the fish for food.
What is the maximum age recorded for this fish?
The maximum recorded age is 48 years. Growth slows considerably after ten years, and they reach maturity between thirteen and seventeen years old, depending on sex.
Good reading and sources
- Antarctic toothfish on WikipediaEncyclopedia
- More photos on Wikimedia CommonsPhotos
- Wikidata recordOpen data
The facts on this page come from the Wikipedia article "Antarctic toothfish", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.
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