• 13 parts
  • Checked September 2026

Parts of a Tuna

A tuna from the side, then the same fish divided into its three cuts.

Parts of a Tuna

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12 13
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Write the name of each numbered part.Answer key

  1. Tail fin
  2. Eye
  3. First dorsal fin
  4. Second dorsal fin
  5. Pectoral fin
  6. Pelvic fin
  7. Anal fin
  8. Finlets
  9. Caudal keel
  10. Caudal peduncle
  11. Akami
  12. Otoro
  13. Chutoro

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the parts of a whale

All 13 parts on the diagram

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The outside of the fish 10

  1. Tail fin Curved like a crescent moon, with pointed tips. Its other name is the caudal fin.
  2. Eye A bluefin's eye is small next to those of other tunas.
  3. First dorsal fin Held up by spines. It can fold down flat into a groove along the back.
  4. Second dorsal fin On a bluefin, taller than the first dorsal fin and reddish brown.
  5. Pectoral fin One on each side. A bluefin's pectoral fins are short for a tuna.
  6. Pelvic fin The pelvic fins sit under the pectoral fins' base. They fold away when the fish swims fast.
  7. Anal fin Matches the second dorsal fin above it. It starts a little farther back.
  8. Finlets Tuna have seven to ten small ones behind the second dorsal fin. A row also sits behind the anal fin. They cannot fold down.
  9. Caudal keel A ridge that steadies the tail stalk. A tuna has three keels on each side.
  10. Caudal peduncle The thin part of the body where the tail fin attaches.

The cuts 3

  1. Akami The lean, red meat from the back and inside of the fish. It has the least fat of the three cuts.
  2. Otoro The fattiest cut, from the belly just behind the head.
  3. Chutoro A medium-fatty cut, from the belly farther back toward the tail.

How this list was compiled: Every name checked on 2026-09-30. The outside of the fish: (1) Florida Museum of Natural History, University of Florida, Bluefin Tuna species profile, https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/thunnus-thynnus/ (two dorsal fins with a small space between them, the second taller than the first and followed by 7 to 10 finlets; anal fin; short pectoral fins; pelvic fins; three keels on the caudal peduncle; crescent caudal (tail) fin; small eye); (2) Wikipedia, text only: Tuna, https://en.wikipedia.org/wiki/Tuna (two dorsal fins, the first folding into a groove; seven to ten finlets; pelvic fins below the base of the pectoral fins; lunate tail; caudal peduncle with three keels on each side; finlets rayless and non-retractable); (3) NOAA Fisheries, Pacific bluefin tuna and Western Atlantic bluefin tuna, https://www.fisheries.noaa.gov/species/pacific-bluefin-tuna and https://www.fisheries.noaa.gov/species/western-atlantic-bluefin-tuna (second dorsal fin reddish brown, short pectoral fins, a series of small fins from the second dorsal fin to the tail, small eyes). The cuts: (4) G. P. Ashenden and G. W. Kitson, The Japan Tuna Market, Pacific Islands Development Program, East-West Center, 1987, https://scholarspace.manoa.hawaii.edu/bitstreams/96a0ac9c-0e2d-4a46-a4c6-5f0a9f44b8ac/download (otoro, chutoro and akami; the toro portions come from the belly; akami has the least fat); (5) S. Van Kampen-Lewis, MBA thesis, University of Hawaii at Manoa, 2008, https://scholarspace.manoa.hawaii.edu/bitstreams/6209b01d-70aa-4827-8794-63401e946216/download (o-toro on the bottom side just behind the head; chu-toro from the ventral region down to just in front of the tail; the redder, leaner meat of the top half is akami); (6) Wikipedia, text only: Toro (sushi), https://en.wikipedia.org/wiki/Toro_(sushi). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work

How it works

The top drawing names the outside of a bluefin-type tuna. The bottom drawing is the same fish with its side divided into the three cuts a sushi counter names.

Read the full guide

The fish, then the cuts

Numbers 1 to 10 are on the outside: the tail fin, the eye, the two dorsal fins on the back, the pectoral fin on the side, the pelvic and anal fins underneath, the finlets, and the caudal keel on the caudal peduncle. Numbers 11 to 13 are the cuts: akami along the back, otoro in the belly behind the head, and chutoro in the belly toward the tail.

  • Two dorsal fins, close together: the first is held up by spines, and on a bluefin the second is the taller one.
  • Finlets come in two rows: one behind the second dorsal fin and one behind the anal fin.

Questions and answers

What are the small fins on a tuna called?

Finlets. They run in a row from the second dorsal fin to the tail, with a matching row behind the anal fin. A tuna has seven to ten, and they cannot fold down.

Where do akami, chutoro and otoro come from on a tuna?

Otoro is the fattiest cut, from the belly just behind the head. Chutoro is medium-fatty, from the belly farther back toward the tail. Akami is the lean, red meat of the back and the inside.

What is toro?

Toro is the fatty meat of a tuna, which comes mostly from the belly. It is sold in two grades: otoro, the fattiest, and chutoro, which has less fat.

What is the keel on a tuna's tail?

A ridge on the side of the caudal peduncle, the thin stalk that carries the tail fin. A tuna has three keels on each side.

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