What Category Does Tuna Fall Under? A Scientific Look

November 8, 2025 •

3 min read

Tuna is one of the world's most consumed fish, but its classification is often misunderstood. The question, 'what category does tuna fall under?', leads us to its proper scientific placement as a member of the mackerel family and the Thunnini tribe.

Quick Summary

Tuna belongs to the Thunnini tribe, a subgroup of the Scombridae (mackerel) family of saltwater fish, comprising 15 species across five genera. It is known for its migratory behavior, speed, and unique ability to regulate its body temperature, unlike most fish.

Key Points

Tuna is a saltwater fish: Specifically, it belongs to the tribe Thunnini and the mackerel family (Scombridae).
Tuna is not a mammal: Though sometimes mistaken for one due to its endothermic abilities, tuna is a fish with gills and does not possess mammalian characteristics like hair or mammary glands.
The Thunnini tribe defines tunas: This tribe includes 15 species across five genera, such as the 'true tunas' in the genus Thunnus and other species like skipjack in the genus Katsuwonus.
Different species have different characteristics: Albacore, skipjack, yellowfin, and bluefin tuna each have distinct flavor profiles, mercury levels, and ideal culinary uses.
Tuna are powerful, warm-blooded predators: They possess a unique circulatory system (rete mirabile) that allows them to maintain a warmer body temperature than their surroundings, enabling high-speed swimming.

Tuna's Place in the Animal Kingdom

To understand what category tuna falls under, we must journey through its biological classification. At the highest level, tuna is an animal (Kingdom: Animalia) and a chordate (Phylum: Chordata). However, its more specific placement reveals more about its nature and relatives.

Tuna's full scientific classification is:

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii (ray-finned fishes)
Order: Scombriformes
Family: Scombridae (mackerel family)
Tribe: Thunnini (tunas)

The Mackerel Family (Scombridae)

Within the extensive and diverse mackerel family, Scombridae, tuna holds a special place. This family includes many well-known marine predators, such as mackerels, bonitos, and tuna. The family is characterized by a sleek, streamlined body and a deeply forked tail, adaptations for swift movement through water. The Scombridae family is further divided into tribes, with the Thunnini tribe being the most highly evolved.

The Thunnini Tribe: The 'True' Tunas

The tribe Thunnini is what officially defines a tuna. This group includes 15 species across five genera, with the most commercially important species belonging to the genus Thunnus. This is where terms like 'true tunas' and 'minor tunas' come into play, referring to the specific biological relationships within the tribe.

Key Characteristics of Tuna

Tuna are not ordinary fish. They possess several unique characteristics that set them apart from their relatives:

Endothermy: Unlike most fish, which are cold-blooded (ectothermic), tuna have the remarkable ability to maintain a body temperature warmer than the surrounding water. This is achieved through a specialized network of blood vessels known as the rete mirabile, or "wonderful net," which acts as a counter-current heat exchanger. This feature boosts muscle efficiency, allowing for higher swimming speeds and enabling them to inhabit a wider range of ocean temperatures.
Streamlined Body: Tuna have a sleek, hydrodynamic, torpedo-shaped body designed for incredible speed and endurance. Their dorsal fins can even retract into grooves to reduce drag while swimming at high speeds.
Powerful Swimmers: As obligate ram ventilators, tuna must constantly swim with their mouths open to force water over their gills for oxygen. This constant motion, combined with their streamlined bodies, makes them one of the fastest pelagic fish in the ocean.
Apex Predators: As apex predators, tuna play a vital role in marine ecosystems, controlling populations of smaller fish and squid. This also means they accumulate higher levels of contaminants like mercury due to bioaccumulation up the food chain.

Popular Tuna Species and Their Categories

Different species of tuna fall into specific categories based on their classification and commercial use. Here is a look at some of the most prominent:

Albacore (Thunnus alalunga): Known for its light-colored flesh, often marketed as 'white tuna.' It belongs to the 'true tuna' genus Thunnus.
Skipjack (Katsuwonus pelamis): This is the most commonly fished tuna species and is often used for canned 'chunk light' tuna. Though considered a tuna, it is not in the Thunnus genus.
Yellowfin (Thunnus albacares): A popular choice for steaks and sushi, also known as 'ahi.' It's a 'true tuna' with a milder flavor than skipjack.
Bluefin (Thunnus thynnus, T. orientalis, T. maccoyii): A large, prized species, especially in the sushi market. The Atlantic bluefin is one of the largest and most valuable species.

A Comparison of Common Tuna Categories


Feature	Albacore (White Tuna)	Skipjack (Light Tuna)	Yellowfin (Ahi)	Bluefin
Scientific Tribe	Thunnini	Thunnini	Thunnini	Thunnini
Scientific Genus	Thunnus	Katsuwonus	Thunnus	Thunnus
Mercury Levels	Moderate to high; best consumed in moderation	Lowest of the common species; can be eaten more frequently	Moderate; typically higher than skipjack	Highest of all tuna species
Flesh Color	Very light, almost white	Pinkish	Pink to deep red	Deep red
Flavor Profile	Mild, firm, steak-like texture	Strong, robust, 'fishier' flavor	Mild, firm texture	Rich, fatty, and highly prized for sushi
Common Use	Canned white tuna, firm steaks	Canned chunk light tuna, salads, and casseroles	Steaks, sushi, and sashimi	Premium sushi and sashimi

Conclusion

In summary, tuna falls under the category of a saltwater fish and is more specifically classified as a member of the Thunnini tribe, which is a subgroup of the mackerel family (Scombridae). This scientific classification helps to clarify its place in the marine world, distinguishing it from other fish and mammals. Beyond the biological family tree, tuna is categorized commercially based on its species (e.g., skipjack, albacore), influencing its culinary use, nutritional content, and market value. For consumers, understanding this classification provides context for their seafood choices and helps demystify where this popular and important fish belongs in the vast ocean ecosystem.

Frequently Asked Questions

Tuna is a fish, not a mammal. While they are one of the few species of fish that can regulate their body temperature, they lack all other mammalian traits like mammary glands and hair, and they breathe through gills.

White tuna is almost always albacore tuna, known for its milder flavor and lighter-colored flesh. Light tuna is typically a smaller species, like skipjack, and has a stronger, 'fishier' flavor and darker, pinkish flesh.

The nickname 'chicken of the sea' was originally used by a tuna company to promote canned albacore tuna, emphasizing its light-colored flesh and mild flavor as an alternative to chicken. This marketing phrase led to some public confusion, though tuna is clearly a fish.

Tuna belongs to the Scombridae family, also known as the mackerel family. This family includes a wide range of marine fish that share characteristics like streamlined bodies and powerful swimming abilities.

The most common tuna species used for canning are skipjack and albacore. Skipjack is used for 'chunk light' tuna, while albacore is used for 'solid white' tuna.

Yes, bluefin tuna is a specific species (Thunnus thynnus) known for its large size and high fat content, making it highly prized for sushi and sashimi. It is significantly more expensive and generally contains higher levels of mercury than other types like skipjack.

Tuna are highly migratory, pelagic fish that live in the open ocean, away from the continental shelf. They inhabit temperate and tropical waters worldwide and are known for traveling vast distances across ocean basins.