--- title: "Antarctic Icefish (Champsocephalus gunnari) | AnimalTracks.wiki" description: "A Southern Ocean fish with no working red blood cells, whose nearly clear blood carries oxygen dissolved in plasma, along with its own antifreeze." image: "https://animaltracks.wiki/images/animals/antarctic-icefish-1.webp" published: "2026-09-05" updated: "2026-09-17" --- # Antarctic Icefish (*Champsocephalus gunnari*) > **Status**: Checked against 6 sources, listed under Sources below. > **Tagline**: A Southern Ocean fish with no working red blood cells, whose nearly clear blood carries oxygen dissolved in plasma, along with its own antifreeze. > **Soundtrack Vibe**: Glacial Ambient & Drone Soundscapes // Biosphere, "Kobresia" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/5O6MFTh1rd9PeN8XEn1yCS) | [YouTube](https://www.youtube.com/watch?v=vvmt_q-B-sA) > **Vibe Match**: Deep sub-zero drone textures and translucent atmospherics for a fish whose nearly colorless blood has no hemoglobin and carries oxygen only dissolved in its plasma, at under 10 percent of the capacity of its red-blooded relatives. ## Biological Superpowers & Stats - **Taxonomy**: *Champsocephalus gunnari* - **Danger Level**: Low - **Conservation Status**: Not Evaluated ([IUCN Red List](https://www.iucnredlist.org/)) - **Superpower**: Belongs to the only vertebrate family that lacks working hemoglobin genes and working red blood cells: its blood carries oxygen dissolved in the plasma instead. - **Habitat**: Island shelves of the sub-Antarctic and the Antarctic Peninsula, mainly around Heard Island, the McDonald Islands, Kerguelen and South Georgia, usually at depths of 30 to 250 meters - **Diet**: Krill, mysids and small fish, including juvenile icefish - **Tags**: fish, antarctic, evolutionary-marvel, extreme-adaptation ## Natural History & Behavior ## Almost Clear Blood Cut into an **Antarctic Icefish** (*Champsocephalus gunnari*, the mackerel icefish) and its blood looks nearly colorless. It belongs to Channichthyidae, the icefish family, the only vertebrates that lack functional red blood cells and functional hemoglobin genes. Hemoglobin is the red pigment that carries oxygen in blood. Without it, icefish blood carries oxygen only dissolved in the plasma. That gives it under 10 percent of the oxygen-carrying capacity of a closely related red-blooded Antarctic fish's blood. > **An Expensive Trait** Losing hemoglobin, and in some icefish species myoglobin, another oxygen-binding protein, does not appear to have given these fish any advantage. Losing hemoglobin raised the energy cost of circulating blood, and losing myoglobin reduced heart performance, yet the losses are fixed traits in icefishes: every fish of an affected species inherits them. ## Building Around the Loss 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, the tiny structures inside cells that use oxygen to release energy. 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. A mackerel icefish's blood carries compounds that prevent it from freezing in the Southern Ocean's sub-zero water, and it lacks myoglobin as well as hemoglobin. ## Home Waters and Size Mainly found around Heard Island, the McDonald Islands, Kerguelen and South Georgia, the mackerel icefish is a schooling fish of the Southern Ocean's island shelves. It has 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. Around Heard Island, CCAMLR, the international commission that manages Antarctic fishing, gives its maximum as around 45 centimeters and 6 years. 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. It usually lives at depths of 30 to 250 meters and has been found down to 700. Schools spend the day near the seafloor and the night in midwater, a round trip made every 24 hours. ## Hunting, Being Hunted, and a Managed Fishery Mackerel icefish eat krill and mysids, small shrimp-like crustaceans, along with small fish, including young icefish. Other fish prey on them, and their predators also include gentoo penguins and Antarctic fur seals. They reach reproductive maturity at three to four years old, and adults move inshore to spawn over two to three months in autumn and winter. Females lay 10,000 to 20,000 eggs, which stay near the seabed for about three months before hatching. Australia's Heard Island and McDonald Islands Fishery targets the species with bottom trawls. Its catch limit for the 2024-25 season was 1,824 tonnes, and the fisheries authority's page, last updated in July 2025, lists the stock as not overfished and not subject to overfishing. ## Frequently Asked Questions ### How can a fish survive with no red blood cells or hemoglobin? Icefish, the family Channichthyidae, are the only vertebrates that lack functional red blood cells and functional hemoglobin genes. Instead of carrying oxygen bound to hemoglobin, 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 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. *(Source: [Kim et al. 2019]())* ### How does the mackerel icefish avoid freezing in sub-zero water? Its blood carries compounds that prevent it from freezing. The same blood is nearly clear because it lacks hemoglobin, and it lacks myoglobin, another oxygen-binding protein, as well. *(Source: [Australian Fisheries Management Authority]())* ### Is losing hemoglobin an advantage for icefish? Not as far as researchers can tell. 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. Losing hemoglobin raised the energy cost of circulating blood, and losing myoglobin reduced heart performance. 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. *(Source: [Sidell & O'Brien 2006]())* ## Sources 1. [Kim et al. (2019). Antarctic blackfin icefish genome reveals adaptations to extreme environments. Nature Ecology & Evolution.]() 2. [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.]() 3. [Mackerel icefish. Australian Fisheries Management Authority.]() 4. [Antarctic fish. Australian Antarctic Program.]() 5. [Species Description 2023: Champsocephalus gunnari. CCAMLR Secretariat, 2023.]() 6. [Antarctic wildlife. British Antarctic Survey.]() *Published September 5, 2026. Last updated September 17, 2026.* ```json { "@context": "https://schema.org", "@graph": [ { "@type": "Article", "@id": "https://animaltracks.wiki/animals/antarctic-icefish/#article", "isPartOf": { "@id": "https://animaltracks.wiki/#website" }, "headline": "Antarctic Icefish (Champsocephalus gunnari) | AnimalTracks.wiki", "description": "A Southern Ocean fish with no working red blood cells, whose nearly clear blood carries oxygen dissolved in plasma, along with its own antifreeze.", "image": [ "https://animaltracks.wiki/images/animals/antarctic-icefish-1.webp" ], "datePublished": "2026-09-05", "dateModified": "2026-09-17", "author": [ { "@type": "Organization", "name": "AnimalTracks.wiki Editorial Team", "url": "https://animaltracks.wiki" } ], "publisher": { "@type": "Organization", "@id": "https://animaltracks.wiki/#organization", "name": "AnimalTracks.wiki", "url": "https://animaltracks.wiki", "logo": { "@type": "ImageObject", "url": "https://animaltracks.wiki/icon-512.png" } }, "mainEntityOfPage": "https://animaltracks.wiki/animals/antarctic-icefish/", "citation": [ { "@type": "ScholarlyArticle", "name": "Antarctic blackfin icefish genome reveals adaptations to extreme environments", "url": "https://doi.org/10.1038/s41559-019-0812-7", "author": "Kim et al.", "datePublished": "2019", "isPartOf": { "@type": "Periodical", "name": "Nature Ecology & Evolution" }, "identifier": "doi:10.1038/s41559-019-0812-7" }, { "@type": "ScholarlyArticle", "name": "When bad things happen to good fish: the loss of hemoglobin and myoglobin expression in Antarctic icefishes", "url": "https://doi.org/10.1242/jeb.02091", "author": "Sidell & O'Brien", "datePublished": "2006", "isPartOf": { "@type": "Periodical", "name": "Journal of Experimental Biology" }, "identifier": "doi:10.1242/jeb.02091" }, { "@type": "CreativeWork", "name": "Mackerel icefish", "url": "https://www.afma.gov.au/fisheries-management/species/mackerel-icefish", "publisher": { "@type": "Organization", "name": "Australian Fisheries Management Authority" } }, { "@type": "CreativeWork", "name": "Antarctic fish", "url": "https://www.antarctica.gov.au/about-antarctica/animals/fish/", "publisher": { "@type": "Organization", "name": "Australian Antarctic Program" } }, { "@type": "CreativeWork", "name": "Species Description 2023: Champsocephalus gunnari", "url": "https://fishdocs.ccamlr.org/SpDescr_ANI_2023.pdf", "datePublished": "2023", "publisher": { "@type": "Organization", "name": "CCAMLR Secretariat" } }, { "@type": "CreativeWork", "name": "Antarctic wildlife", "url": "https://bas.ac.uk/about/antarctica/wildlife/fish-and-squid", "publisher": { "@type": "Organization", "name": "British Antarctic Survey" } } ], "about": { "@type": "Taxon", "name": "Antarctic Icefish", "scientificName": "Champsocephalus gunnari", "description": "Belongs to the only vertebrate family that lacks working hemoglobin genes and working red blood cells: its blood carries oxygen dissolved in the plasma instead." } }, { "@type": "FAQPage", "@id": "https://animaltracks.wiki/animals/antarctic-icefish/#faq", "mainEntity": [ { "@type": "Question", "name": "How can a fish survive with no red blood cells or hemoglobin?", "acceptedAnswer": { "@type": "Answer", "text": "Icefish, the family Channichthyidae, are the only vertebrates that lack functional red blood cells and functional hemoglobin genes. Instead of carrying oxygen bound to hemoglobin, 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 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.", "citation": { "@type": "ScholarlyArticle", "name": "Antarctic blackfin icefish genome reveals adaptations to extreme environments", "url": "https://doi.org/10.1038/s41559-019-0812-7", "author": "Kim et al.", "datePublished": "2019", "isPartOf": { "@type": "Periodical", "name": "Nature Ecology & Evolution" }, "identifier": "doi:10.1038/s41559-019-0812-7" } } }, { "@type": "Question", "name": "How does the mackerel icefish avoid freezing in sub-zero water?", "acceptedAnswer": { "@type": "Answer", "text": "Its blood carries compounds that prevent it from freezing. The same blood is nearly clear because it lacks hemoglobin, and it lacks myoglobin, another oxygen-binding protein, as well.", "citation": { "@type": "CreativeWork", "name": "Mackerel icefish", "url": "https://www.afma.gov.au/fisheries-management/species/mackerel-icefish", "publisher": { "@type": "Organization", "name": "Australian Fisheries Management Authority" } } } }, { "@type": "Question", "name": "Is losing hemoglobin an advantage for icefish?", "acceptedAnswer": { "@type": "Answer", "text": "Not as far as researchers can tell. 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. Losing hemoglobin raised the energy cost of circulating blood, and losing myoglobin reduced heart performance. 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.", "citation": { "@type": "ScholarlyArticle", "name": "When bad things happen to good fish: the loss of hemoglobin and myoglobin expression in Antarctic icefishes", "url": "https://doi.org/10.1242/jeb.02091", "author": "Sidell & O'Brien", "datePublished": "2006", "isPartOf": { "@type": "Periodical", "name": "Journal of Experimental Biology" }, "identifier": "doi:10.1242/jeb.02091" } } } ] }, { "@type": "MusicRecording", "name": "Kobresia", "byArtist": { "@type": "MusicGroup", "name": "Biosphere" }, "genre": "Glacial Ambient & Drone Soundscapes", "url": "https://open.spotify.com/track/5O6MFTh1rd9PeN8XEn1yCS" } ] } ```