Both of these fish species live in some of the world’s largest oceans. The bluefin tuna is known for its size, speed, and globality, while the yellowfin is smaller and more suited to particular environments. Learn more about the similarities and differences below!

Bluefin Tuna (left) vs Yellowfin Tuna (Right) Visual Comparison


Main Differences Between a Bluefin Tuna and a Yellowfin Tuna

Here are the top four main differences between bluefin and yellowfin tuna: 

  • Appearance: The bluefin tuna is known for its blue dorsal and anal fins, while the yellowfin tuna has a bright yellow variation. The yellowfin also has far more pronounced fins, making them ‘sharp’ looking.
  • Size: There is a big size difference despite the yellowfin tuna weighing 400lbs. The bluefin tuna dwarfs it as it can weigh up to 1500lbs.
  • Habitat: The bluefin tuna is known for inhabiting the Atlantic and Pacific Oceans, while the yellowfin mostly sticks to tropical and subtropical seas, such as the Indian Ocean.
  • Diet: Both species prey on small marine animals. These consist of small crustaceans, squid, and many slow and fast-moving fish such as mackerel and herring.

We’ll explore these differences and exciting facts about these two fish below.

Bluefin Tuna

The bluefin tuna is the biggest tuna in the ocean. Sometimes known as the Pacific bluefin tuna, or Atlantic bluefin tuna, they are migratory fish that are located all over the world. Despite their tasty culinary reputation, they are actually oceanic apex predators.

Appearance 

One of the trademarks of the Bluefin tuna is its size. It is considered the largest tuna on earth. They rely on their speed for their hunting prowess, largely due to their body shape. They can be described as ‘missile-like, with a streamlined body.

Despite their speed, they can grow to immense sizes, some being recorded to weigh 680 kg or 1500 lbs.

Bluefin tuna typically have a dark blue and silver pattern that distinguishes them from other tuna species. The blue section covers the upper part of the body, while the silver makes up the underside.

Bluefin tuna have torpedo-like bodies
Bluefin tuna have torpedo-like bodies

Credit: aes256, CC BY 2.1 JP


Habitat

Bluefin tuna are found all over the world, in some of the biggest oceans. As their names describe, many populations can be found in the Atlantic Ocean and the Pacific Oceans. As a migratory species, they don’t have one static habitat.

Diet 

Many small marine species are a vital part of the bluefin tuna’s diet. They will dive to significant depths to hunt for their prey. Their prey consists of small crustaceans, like shrimp and small fish. Some of these fish are mackerel, sardines, and herring.

Overfishing is one of the largest threats to the bluefin tuna's existence
Overfishing is one of the largest threats to the bluefin tuna’s existence

Credit: Asc1733, CC BY-SA 4.0


Threats 

The most prevalent threat to bluefin tuna, and most tuna species, is human intervention. They are currently considered under threat by the IUCN.

As the need for food increases by the day, more and more fish are being extracted from the ocean, and bluefin tuna is at the top of the list. Aquaculture has been implemented to counteract the declining wild population. However, it is not currently at sustainable levels.

Other hazards such as oil spills have been a constant threat to the bluefin tuna and marine life as a whole. An example of this was in 2010, when 4.9 million barrels of crude oil made their way into the Atlantic Ocean via the Gulf of Mexico.

The bluefin is known to have up to 70 different types of parasites. However, they are considered benign.

Yellowfin Tuna 

The yellowfin tuna is a relatively large species of tuna. They are mainly located in tropical seas. They are sometimes referred to as ‘ahi’. This originates from the Hawaiian language.

Appearance

The yellowfin can reach up to 180 kg, or 400lbs. Although this is seen as a big fish, they pale compared to the bluefin species. Their name comes from their distinctive bright yellow second dorsal fin and anal fin.

Yellowfin tuna have very distinctive fins
Yellowfin tuna have very distinctive fins

Credit: Elias Levy (CC BY 2.0)


Diet

Speed is commonplace within tuna species, and as predators, this suits them perfectly. The yellowfin is no different. They are built like torpedos which allow them to hunt faster-moving fish. They feed on crustaceans, mackerel, squid, and many other types of marine animals.

Habitat

The yellowfin tuna is heavily based in the tropical and sub-tropical oceans. They prefer to inhabit the upper layers of the water column. They are considered epipelagic.

Unlike some of their close relatives, the yellowfin stays at about 100m depth, which is equivalent to around 300ft. However, they have been known to dive to extreme depths when required.

Interestingly, the yellowfin tuna will sometimes school with other tuna species, such as skipjack tuna.

Yellowfin tuna are under threat from overfishing
Yellowfin tuna are under threat from overfishing


Threats

The yellowfin tuna is threatened by predation from larger marine animals. Great white sharks and killer whales are some of the hunters capable of catching these super fast tuna. Normally, at up to 47 mph, the yellowfin can escape from many predators.

Alongside the human threat of habitat loss, overfishing, and getting stuck in nets, they are sought out by sports fishermen due to their speed and agility. However, sports fishermen tend to throw them back into the ocean to maintain sustainability within the species.

FAQs

Is ahi tuna the same as bluefin?

No, ahi tuna is the Hawaiian name for the yellowfin species of tuna. Other names for bluefin tuna are Atlantic tuna and Pacific tuna.

What is another name for bluefin tuna?

The bluefin tuna has a few different names. They have been referred to as Atlantic bluefin, Pacific bluefin, northern bluefin, giant bluefin, and tunny.

Why is bluefin tuna so valuable?

Bluefin tuna are so valuable because a sustainable way to breed them in captivity has not yet been mastered. Due to this, their source is largely based on wild populations. This demands more time and resources to catch them, hence why they command such a high price.