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July 26, 2026Sources cited
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Science & Nature • Fish

Tuna

Tuna are large, fast-swimming saltwater fishes in the tribe Thunnini, within the mackerel family Scombridae.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Tuna are large, fast-swimming saltwater fishes in the tribe Thunnini, within the mackerel family Scombridae. They are found in oceans worldwide and include several commercially important species such as bluefin, yellowfin, albacore, and skipjack. Tuna are valued as food and are also sought after as game fish.

Classification

Tuna belong to the tribe Thunnini in the family Scombridae, which also includes mackerels and bonitos. The group is commonly divided into several genera, with many sources identifying about 15 tuna species overall.

Physical characteristics

Tuna have streamlined bodies built for speed and endurance in open water. Many species are large, with sizes ranging from small bullet tuna to very large bluefin tuna.

Ecology and behaviour

Tuna are active predatory fish that feed on smaller fish, squid, shellfish, and sometimes plankton. They are pelagic and many species travel widely across ocean basins.

Human use

Tuna are among the world’s most commercially important fish and are widely eaten fresh or canned. They are also popular in sport fishing and are central to many fisheries management and sustainability discussions.

Key facts

  • Tuna are not one single fish species but a group of related fish.
  • They are oceanic, pelagic fishes found in warm and temperate seas.
  • Tuna are powerful swimmers and many species migrate long distances.
  • Several tuna species are major commercial fisheries species.
  • The group includes both small species and very large species such as Atlantic bluefin tuna.
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Canadian context

Tuna is important to Canadian readers as a widely consumed seafood species and as part of Canada’s interest in sustainable ocean fisheries and international tuna management.

Frequently asked questions

What is tuna?
Tuna are a group of saltwater fish in the tribe Thunnini, within the mackerel family Scombridae.
How many species of tuna are there?
Sources commonly describe about 15 tuna species worldwide, though some references use narrower definitions for “true tunas.”
Where do tuna live?
Tuna live in marine waters around the world, especially in open-ocean pelagic habitats.
What do tuna eat?
Tuna are predators that eat fishes, squid, shellfish, and sometimes plankton.
Why are tuna important to people?
Tuna are highly valued as food and are also important in commercial fishing and recreational sport fishing.

References

  1. Britannica — https://www.britannica.com/animal/tuna-fish
    Supports: Tuna classification in Scombridae; general characteristics and commercial importance.
  2. Wikipedia — https://en.wikipedia.org/wiki/Tuna
    Supports: Tuna as a group in Thunnini; approximate species count and size range.
  3. National Geographic — https://www.nationalgeographic.com/animals/fish/facts/tuna
    Supports: Tuna diversity, pelagic habitat, predatory diet, and broad biological overview.
  4. Marine Stewardship Council — https://www.msc.org/what-you-can-do/eat-sustainable-seafood/fish-to-eat/tuna
    Supports: Tuna as a widely eaten fish and notes on common species and consumption forms.
  5. Smithsonian Ocean Portal — https://ocean.si.edu/ocean-life/fish/big-tunas
    Supports: Tuna as large, athletic predatory fish and broader family context.