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What the sources say

Antarctic IcefishChampsocephalus gunnari

Every figure, record and mechanism on the Antarctic Icefish profile was written from a source, and this is the working table behind it: 55 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Kim et al. 2019

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

The page saysno working red blood cells
The source saysThese remarkable animals are the only vertebrates that lack functional red blood cells and functional haemoglobin genesNote: '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
The page saysoxygen dissolved
The source saysIcefish blood carries oxygen solely in physical solutionNote: 'dissolved' = 'in physical solution'
The page saysthe only vertebrate family that lacks working hemoglobin genes and working red blood cells
The source saysIcefishes (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 page saysthe only vertebrates that lack functional red blood cells and functional hemoglobin genes
The source saysThese remarkable animals are the only vertebrates that lack functional red blood cells and functional haemoglobin genes
The page saysicefish blood carries oxygen only dissolved in the plasma
The source saysIcefish blood carries oxygen solely in physical solutionNote: 'only' = 'solely'; 'plasma' from BAS's 'transports oxygen through its blood plasma'
The page saysThat gives it under 10 percent of the oxygen-carrying capacity of a closely related red-blooded Antarctic fish's blood
The source saysIcefish 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
The page saysIcefish 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
The source saysIcefishes 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 morphologyNote: 'pump more blood per beat' defines stroke volume
The page saysIcefish 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
The source sayseight 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 lipidsNote: 'open water' = 'water column'
The page saysthe Southern Ocean's sub-zero water
The source saysas the Southern Ocean cooled to sub-zero temperatures
The page saysthe only vertebrates that lack functional red blood cells and functional hemoglobin genes
The source saysThese remarkable animals are the only vertebrates that lack functional red blood cells and functional haemoglobin genesNote: FAQ 1
The page saystheir blood carries it only dissolved, which gives it under 10 percent of the oxygen-carrying capacity of closely related red-blooded Antarctic fish
The source saysIcefish 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 fishesNote: FAQ 1
The page saysIcefish 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
The source saysIcefishes 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 morphologyNote: FAQ 1
The page sayscarries oxygen only dissolved in its plasma, at under 10 percent of the capacity of its red-blooded relatives
The source saysIcefish 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 fishesNote: 'plasma' from bas-antarctic-wildlife: "transports oxygen through its blood plasma"

Source
02

Sidell & O'Brien 2006

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.

The page saysLosing hemoglobin, and in some icefish species myoglobin, another oxygen-binding protein, does not appear to have given these fish any advantage
The source saysTheir loss of hemoglobin (Hb) expression, and in some cases, loss of myoglobin (Mb) expression ... the losses do not appear to be of adaptive valueNote: 'any advantage' paraphrases 'adaptive value'; 'oxygen-binding protein' is Kim et al.'s term for Hb and Mb
The page saysLosing hemoglobin raised the energy cost of circulating blood, and losing myoglobin reduced heart performance
The source saysloss of Hb has led to higher energetic costs for circulating blood, and losses of Mb have reduced cardiac performance
The page saysthe losses are fixed traits in icefishes
The source saysabsences of the proteins are fixed traits in icefishesNote: the gloss 'every fish of an affected species inherits them' defines genetic fixation
The page saysNot as far as researchers can tell
The source saysthe losses do not appear to be of adaptive valueNote: FAQ 3; restates 'do not appear'
The page saysThe 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
The source saysTheir loss of hemoglobin (Hb) expression, and in some cases, loss of myoglobin (Mb) expression ... the losses do not appear to be of adaptive valueNote: FAQ 3; 'does not seem to help them survive' defines adaptive value
The page saysLosing hemoglobin raised the energy cost of circulating blood, and losing myoglobin reduced heart performance
The source saysloss of Hb has led to higher energetic costs for circulating blood, and losses of Mb have reduced cardiac performanceNote: FAQ 3
The page saysThe losses are fixed traits in icefishes anyway, and they led to extensive changes to the cardiovascular system to deliver enough oxygen to working muscles
The source saysabsences 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 musclesNote: FAQ 3

Source
03

Australian Fisheries Management Authority

Mackerel icefish. Australian Fisheries Management Authority.

The page saysnearly clear blood
The source saysThe blood of mackerel icefish is nearly colourless
The page saysits own antifreeze
The source sayscarries compounds that prevent it freezing
The page saysusually at depths of 30 to 250 meters
The source saysusually found at depths of 30–250 metres
The page saysKrill, mysids and small fish
The source saysSmall shrimp-like crustaceans such as krill and mysids
The page saysa schooling fish
The source saysMackerel icefish are a schooling species
The page saysa 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
The source saysMackerel 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.
The page saysAustralia'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
The source saysSize (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
The page saysIt usually lives at depths of 30 to 250 meters and has been found down to 700
The source saysusually found at depths of 30–250 metres. They have been found down to depths of 700 metres.
The page saysits blood looks nearly colorless
The source saysThe blood of mackerel icefish is nearly colourless
The page saysA mackerel icefish's blood carries compounds that prevent it from freezing
The source sayscarries compounds that prevent it freezing
The page saysit lacks myoglobin as well as hemoglobin
The source saysdue to a lack of haemoglobin. The blood also lacks myoglobin
The page saysMackerel icefish eat krill and mysids, small shrimp-like crustaceans
The source saysPrey: Small shrimp-like crustaceans such as krill and mysids.
The page saysOther fish prey on them
The source saysPredators: 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
The page saysThey reach reproductive maturity at three to four years old
The source saysMackerel icefish reach reproductive maturity at 3–4 years of age.
The page saysadults move inshore to spawn over two to three months in autumn and winter
The source saysAdults move inshore for spawning. Spawning occurs over 2–3 months in autumn and winter.
The page saysFemales lay 10,000 to 20,000 eggs, which stay near the seabed for about three months before hatching
The source saysFemales 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
The page saysAustralia's Heard Island and McDonald Islands Fishery targets the species with bottom trawls
The source saysHeard Island and McDonald Islands Fishery Bottom trawl Targeted
The page saysIts catch limit for the 2024-25 season was 1,824 tonnes
The source saysCatch Limit 1,824 tonnes For the 2024–25 Season
The page sayslists the stock as not overfished and not subject to overfishing
The source saysCatch Limit 1,824 tonnes For the 2024–25 Season G;Not subject to overfishing G;Not overfished
The page saysthe fisheries authority's page, last updated in July 2025
The source saysPage last updated: 03/07/2025Note: AFMA dates are day/month/year: 3 July 2025; the status and the page date are on the same page
The page saysIts blood carries compounds that prevent it from freezing
The source sayscarries compounds that prevent it freezingNote: FAQ 2
The page saysThe same blood is nearly clear because it lacks hemoglobin, and it lacks myoglobin, another oxygen-binding protein, as well
The source saysThe blood of mackerel icefish is nearly colourless due to a lack of haemoglobin. The blood also lacks myoglobinNote: FAQ 2; 'because' restates 'due to'; 'another oxygen-binding protein' is Kim et al.'s term for Hb and Mb, a definition
The page saysnearly colorless blood has no hemoglobin
The source saysThe blood of mackerel icefish is nearly colourless due to a lack of haemoglobin.

Source
04

Australian Antarctic Program

Antarctic fish. Australian Antarctic Program.

The page saysmainly around Heard Island, the McDonald Islands, Kerguelen and South Georgia
The source saysThis species is mainly found around the Heard Islands, McDonald Islands, Iles Kerguelen and islands in the south Atlantic (such as South Georgia).
The page saysincluding juvenile icefish
The source saysfeeding on plankton and small fish (including juvenile icefish)
The page saysMainly found around Heard Island, the McDonald Islands, Kerguelen and South Georgia
The source saysThis species is mainly found around the Heard Islands, McDonald Islands, Iles Kerguelen and islands in the south Atlantic (such as South Georgia).
The page saysSchools spend the day near the seafloor and the night in midwater, a round trip made every 24 hours
The source saysIcefish form schools and migrate each 24 hours. They spend the day near the seafloor ... They spend the night in midwater.
The page saysHemoglobin is the red pigment that carries oxygen in blood
The source saysthe red, oxygen carrying pigment haemoglobin in their blood cells
The page saysalong with small fish, including young icefish
The source saysfeeding on plankton and small fish (including juvenile icefish)

Source
05

CCAMLR Secretariat 2023

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

The page saysIsland shelves of the sub-Antarctic and the Antarctic Peninsula
The source saysconfined to the island shelves of the sub-Antarctic and the Antarctic Peninsula
The page saysa schooling fish of the Southern Ocean's island shelves
The source saysMackerel icefish are endemic to the Southern Ocean and confined to the island shelves
The page saysAround Heard Island, CCAMLR, the international commission that manages Antarctic fishing, gives its maximum as around 45 centimeters and 6 years
The source saysIn 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
The page saystheir predators also include gentoo penguins and Antarctic fur seals
The source saysIcefish predators include Antarctic fur seals ( Arctocephalus gazella ) and gentoo penguins ( Pygoscelis papua ).

Source
06

British Antarctic Survey

Antarctic wildlife. British Antarctic Survey.

The page sayscarries oxygen dissolved in plasma
The source saysIt lacks red blood cells and transports oxygen through its blood plasma
The page saysits blood carries oxygen dissolved in the plasma instead
The source saystransports oxygen through its blood plasma

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.