How to Tell the Difference Between Bluefin and Yellowfin Tuna

Written by natalie schwab
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How to Tell the Difference Between Bluefin and Yellowfin Tuna
Both yellowfin and bluefin tuna are caught for food. (Jupiterimages/Comstock/Getty Images)

Bluefin and yellowfin tuna are quite similar in appearance with one big thing in common: they are both hunted for food. Bluefin are especially prized for their value in sushi and are endangered worldwide. If you're out fishing and think you've caught one of these two types of tuna, pay attention to characteristics like body shape, colour and size to determine which of the two types you have caught.

Skill level:
Moderately Easy


  1. 1

    Observe the finlets on your fish. The finlets are the tiny fins that run down the back of the fish. The finlets on a yellowfin tuna are yellow and trimmed in black. The finlets on a bluefin tuna are steely blue.

  2. 2

    Look for a gold stripe along the side of the fish. If there is one it is a yellowfin tuna.

  3. 3

    Look at the shape of your fish. A yellowfin tuna has a football shape, while a bluefin tuna is more of a torpedo shape. The length of the pectoral fin is another distinguishing mark: the yellowfin pectoral fin practically reaches the start of the second dorsal fin.

  4. 4

    Check to see if there are spots or wavy lines on the underside of the fish. This is a characteristic of yellowfin tuna. The yellowfin has bright yellow dorsal and anal fins and finlets. By contrast, bluefin are metallic blue on top and shiny silver-white on the bottom.

  5. 5

    Weigh and measure the fish. Bluefin tuna tend to be larger than yellowfin tuna. While a yellowfin tuna can reach a weight of 136kg., a bluefin tuna can grow to 0.454kg and 6.5ft. in length.

  6. 6

    Consider your location. Bluefin tuna are often caught in the deep sea, whereas yellowfin tuna often reside in the open sea and near dropoffs. Yellowfin prefer warm ocean waters, as they are a tropical species. Bluefin are found in colder climes, such as the Gulf of Maine.

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