---
title: "What the sources say about the Antarctic Icefish | AnimalTracks.wiki"
description: "55 claims from the Antarctic Icefish profile, each beside the words of the source that backs it."
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---

# What the sources say about the Antarctic Icefish (*Champsocephalus gunnari*)

> 55 claims from the Antarctic Icefish profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Antarctic Icefish](https://animaltracks.wiki/animals/antarctic-icefish/)

## Kim et al. (2019). Antarctic blackfin icefish genome reveals adaptations to extreme environments. Nature Ecology & Evolution.

https://doi.org/10.1038/s41559-019-0812-7

| The page says | The source says |
| :--- | :--- |
| no working red blood cells | These remarkable animals are the only vertebrates that lack functional red blood cells and functional haemoglobin genes (note: 'working' = 'functional', which Kim et al.'s introduction applies to both red blood cells and haemoglobin genes; CCAMLR notes vestigial erythrocytes, so 'no red blood cells at all' was cut) |
| oxygen dissolved | Icefish blood carries oxygen solely in physical solution (note: 'dissolved' = 'in physical solution') |
| the only vertebrate family that lacks working hemoglobin genes and working red blood cells | Icefishes (suborder Notothenioidei; family Channichthyidae) are the only vertebrates that lack functional haemoglobin genes and red blood cells ... These remarkable animals are the only vertebrates that lack functional red blood cells and functional haemoglobin genes |
| the only vertebrates that lack functional red blood cells and functional hemoglobin genes | These remarkable animals are the only vertebrates that lack functional red blood cells and functional haemoglobin genes |
| icefish blood carries oxygen only dissolved in the plasma | Icefish blood carries oxygen solely in physical solution (note: 'only' = 'solely'; 'plasma' from BAS's 'transports oxygen through its blood plasma') |
| That gives it under 10 percent of the oxygen-carrying capacity of a closely related red-blooded Antarctic fish's blood | Icefish blood carries oxygen solely in physical solution, resulting in an oxygen-carrying capacity per unit of blood volume of less than 10% of that in closely related red-blooded Antarctic notothenioid fishes |
| Icefish evolved what appear to be ways to make up for the missing proteins: enormous hearts that pump more blood per beat for their body size, enhanced networks of blood vessels, and changes to their mitochondria | Icefishes evolved mechanisms that appear to compensate for loss of these oxygen-binding proteins, including enormous hearts with increased stroke volume relative to body size ... enhanced vascular systems ... and changes in mitochondrial density and morphology (note: 'pump more blood per beat' defines stroke volume) |
| Icefish are also among the Antarctic fish groups that became more buoyant by cutting back on heavily mineralized bones and scales and storing more fat, which let them feed in the food-rich open water | eight notothenioid taxa, including the icefishes, evolved to exploit the food-rich water column through increased buoyancy, which was achieved by reducing densely mineralized elements such as bones and scales ... and increasing deposits of lipids (note: 'open water' = 'water column') |
| the Southern Ocean's sub-zero water | as the Southern Ocean cooled to sub-zero temperatures |
| the only vertebrates that lack functional red blood cells and functional hemoglobin genes | These remarkable animals are the only vertebrates that lack functional red blood cells and functional haemoglobin genes (note: FAQ 1) |
| their blood carries it only dissolved, which gives it under 10 percent of the oxygen-carrying capacity of closely related red-blooded Antarctic fish | Icefish blood carries oxygen solely in physical solution, resulting in an oxygen-carrying capacity per unit of blood volume of less than 10% of that in closely related red-blooded Antarctic notothenioid fishes (note: FAQ 1) |
| Icefish evolved what appear to be ways to make up for it: enormous hearts that pump more blood per beat for their body size, enhanced networks of blood vessels, and changes to their mitochondria | Icefishes evolved mechanisms that appear to compensate for loss of these oxygen-binding proteins, including enormous hearts with increased stroke volume relative to body size ... enhanced vascular systems ... and changes in mitochondrial density and morphology (note: FAQ 1) |
| carries oxygen only dissolved in its plasma, at under 10 percent of the capacity of its red-blooded relatives | Icefish blood carries oxygen solely in physical solution, resulting in an oxygen-carrying capacity per unit of blood volume of less than 10% of that in closely related red-blooded Antarctic notothenioid fishes (note: 'plasma' from bas-antarctic-wildlife: "transports oxygen through its blood plasma") |

## Sidell & O'Brien (2006). When bad things happen to good fish: the loss of hemoglobin and myoglobin expression in Antarctic icefishes. Journal of Experimental Biology.

https://doi.org/10.1242/jeb.02091

| The page says | The source says |
| :--- | :--- |
| Losing hemoglobin, and in some icefish species myoglobin, another oxygen-binding protein, does not appear to have given these fish any advantage | Their loss of hemoglobin (Hb) expression, and in some cases, loss of myoglobin (Mb) expression ... the losses do not appear to be of adaptive value (note: 'any advantage' paraphrases 'adaptive value'; 'oxygen-binding protein' is Kim et al.'s term for Hb and Mb) |
| Losing hemoglobin raised the energy cost of circulating blood, and losing myoglobin reduced heart performance | loss of Hb has led to higher energetic costs for circulating blood, and losses of Mb have reduced cardiac performance |
| the losses are fixed traits in icefishes | absences of the proteins are fixed traits in icefishes (note: the gloss 'every fish of an affected species inherits them' defines genetic fixation) |
| Not as far as researchers can tell | the losses do not appear to be of adaptive value (note: FAQ 3; restates 'do not appear') |
| The loss of hemoglobin, and in some icefish species of myoglobin too, does not appear to be of adaptive value, meaning it does not seem to help them survive | Their loss of hemoglobin (Hb) expression, and in some cases, loss of myoglobin (Mb) expression ... the losses do not appear to be of adaptive value (note: FAQ 3; 'does not seem to help them survive' defines adaptive value) |
| Losing hemoglobin raised the energy cost of circulating blood, and losing myoglobin reduced heart performance | loss of Hb has led to higher energetic costs for circulating blood, and losses of Mb have reduced cardiac performance (note: FAQ 3) |
| The losses are fixed traits in icefishes anyway, and they led to extensive changes to the cardiovascular system to deliver enough oxygen to working muscles | absences of the proteins are fixed traits in icefishes ... losses of Hb and Mb have resulted in extensive modifications to the cardiovascular system to ensure adequate oxygen delivery to working muscles (note: FAQ 3) |

## Mackerel icefish. Australian Fisheries Management Authority.

https://www.afma.gov.au/fisheries-management/species/mackerel-icefish

| The page says | The source says |
| :--- | :--- |
| nearly clear blood | The blood of mackerel icefish is nearly colourless |
| its own antifreeze | carries compounds that prevent it freezing |
| usually at depths of 30 to 250 meters | usually found at depths of 30–250 metres |
| Krill, mysids and small fish | Small shrimp-like crustaceans such as krill and mysids |
| a schooling fish | Mackerel icefish are a schooling species |
| a long, spindle-shaped body, a large head with an elongated snout, a large mouth with small teeth, and a bluish-silver body with whitish gills | Mackerel icefish have long spindle-shaped bodies with large heads and elongate snouts. The mouth is large with small teeth. The body is a bluish-silver with whitish gills. |
| Australia's fisheries authority lists the species at up to 66 centimeters, 2 kilograms and 15 years, though it is commonly found at about 35 centimeters | Size (length and weight): Up to 66 cm in length and 2kg. Commonly found at about 35 cm in length. Life span: Up to 15 years. (note: AFMA's species biology box, unscoped to any population; attributed rather than stated as the page's own figure) |
| It usually lives at depths of 30 to 250 meters and has been found down to 700 | usually found at depths of 30–250 metres. They have been found down to depths of 700 metres. |
| its blood looks nearly colorless | The blood of mackerel icefish is nearly colourless |
| A mackerel icefish's blood carries compounds that prevent it from freezing | carries compounds that prevent it freezing |
| it lacks myoglobin as well as hemoglobin | due to a lack of haemoglobin. The blood also lacks myoglobin |
| Mackerel icefish eat krill and mysids, small shrimp-like crustaceans | Prey: Small shrimp-like crustaceans such as krill and mysids. |
| Other fish prey on them | Predators: Other fish, occasionally penguins and seals. (note: the 'occasionally' in the source scopes penguins and seals, which the sentence names only as predators 'also include', from CCAMLR) |
| They reach reproductive maturity at three to four years old | Mackerel icefish reach reproductive maturity at 3–4 years of age. |
| adults move inshore to spawn over two to three months in autumn and winter | Adults move inshore for spawning. Spawning occurs over 2–3 months in autumn and winter. |
| Females lay 10,000 to 20,000 eggs, which stay near the seabed for about three months before hatching | Females produce 10 000‑20 000 eggs. The eggs are relatively large and remain near the sea bed for about 3 months before hatching. (note: AFMA prints '10 000‑20 000' with space-grouped thousands; the script's number matcher reads only comma-grouped thousands) |
| Australia's Heard Island and McDonald Islands Fishery targets the species with bottom trawls | Heard Island and McDonald Islands Fishery Bottom trawl Targeted |
| Its catch limit for the 2024-25 season was 1,824 tonnes | Catch Limit 1,824 tonnes For the 2024–25 Season |
| lists the stock as not overfished and not subject to overfishing | Catch Limit 1,824 tonnes For the 2024–25 Season G;Not subject to overfishing G;Not overfished |
| the fisheries authority's page, last updated in July 2025 | Page last updated: 03/07/2025 (note: AFMA dates are day/month/year: 3 July 2025; the status and the page date are on the same page) |
| Its blood carries compounds that prevent it from freezing | carries compounds that prevent it freezing (note: FAQ 2) |
| The same blood is nearly clear because it lacks hemoglobin, and it lacks myoglobin, another oxygen-binding protein, as well | The blood of mackerel icefish is nearly colourless due to a lack of haemoglobin. The blood also lacks myoglobin (note: FAQ 2; 'because' restates 'due to'; 'another oxygen-binding protein' is Kim et al.'s term for Hb and Mb, a definition) |
| nearly colorless blood has no hemoglobin | The blood of mackerel icefish is nearly colourless due to a lack of haemoglobin. |

## Antarctic fish. Australian Antarctic Program.

https://www.antarctica.gov.au/about-antarctica/animals/fish/

| The page says | The source says |
| :--- | :--- |
| mainly around Heard Island, the McDonald Islands, Kerguelen and South Georgia | This species is mainly found around the Heard Islands, McDonald Islands, Iles Kerguelen and islands in the south Atlantic (such as South Georgia). |
| including juvenile icefish | feeding on plankton and small fish (including juvenile icefish) |
| Mainly found around Heard Island, the McDonald Islands, Kerguelen and South Georgia | This species is mainly found around the Heard Islands, McDonald Islands, Iles Kerguelen and islands in the south Atlantic (such as South Georgia). |
| Schools spend the day near the seafloor and the night in midwater, a round trip made every 24 hours | Icefish form schools and migrate each 24 hours. They spend the day near the seafloor ... They spend the night in midwater. |
| Hemoglobin is the red pigment that carries oxygen in blood | the red, oxygen carrying pigment haemoglobin in their blood cells |
| along with small fish, including young icefish | feeding on plankton and small fish (including juvenile icefish) |

## Species Description 2023: Champsocephalus gunnari. CCAMLR Secretariat, 2023.

https://fishdocs.ccamlr.org/SpDescr_ANI_2023.pdf

| The page says | The source says |
| :--- | :--- |
| Island shelves of the sub-Antarctic and the Antarctic Peninsula | confined to the island shelves of the sub-Antarctic and the Antarctic Peninsula |
| a schooling fish of the Southern Ocean's island shelves | Mackerel icefish are endemic to the Southern Ocean and confined to the island shelves |
| Around Heard Island, CCAMLR, the international commission that manages Antarctic fishing, gives its maximum as around 45 centimeters and 6 years | In Division 58.5.2 , C. gunnari is most abundant at depths of less than 350m in the waters surrounding Heard Island. In this area they grow to a maximum length of around 45cm and a maximum age of 6 years. (note: scoped to Heard Island as the source scopes it; the gloss on CCAMLR (Commission for the Conservation of Antarctic Marine Living Resources) is a definition, not a claim about the fish) |
| their predators also include gentoo penguins and Antarctic fur seals | Icefish predators include Antarctic fur seals ( Arctocephalus gazella ) and gentoo penguins ( Pygoscelis papua ). |

## Antarctic wildlife. British Antarctic Survey.

https://bas.ac.uk/about/antarctica/wildlife/fish-and-squid

| The page says | The source says |
| :--- | :--- |
| carries oxygen dissolved in plasma | It lacks red blood cells and transports oxygen through its blood plasma |
| its blood carries oxygen dissolved in the plasma instead | transports oxygen through its blood plasma |