Hi, astern! You've asked a terrific question, one that I learned the
answer to a couple years ago when I first started learning to prepare
sushi at home.
There are seven different kinds of tuna that are typically offered as
either canned or fresh tuna: albacore, bigeye, blackfin, bluefin,
bonito, skipjack, and yellowfin. Of these, the three found most
commonly in sushi bars are albacore, yellowfin and bluefin. Skipjack,
while occasionally found in sushi bars, is more commonly touted by
Charlie the Tuna as canned tuna.
Albacore, or "white" tuna, is commonly offered as sashimi or sushi in
Japanese restaurants, and can also be found on grocery store shelves
in cans, labeled as albacore, white or "fancy white" tuna.
Yellowfin, also called "ahi", is similarly offered at sushi bars, and
is also found in cans. Ahi constitutes the largest commercial tuna
catch in the US each year, and is marketed as "light" tuna, or just
plain tuna. (Skipjack - which constitutes the second largest
commercial catch - is also marketed as "light" tuna, and is among the
least expensive varieties of tuna.)
Bluefin, or "maguro" tuna, is not found in cans. Rather, it is sold
as sushi or sashimi, as fresh tuna steaks, or flash frozen as tuna
steaks. Maguro is a deep, pinkish red color when raw, and is highly
prized among sushi chefs for its fatty underbelly ("toro"). The toro
is well loved for its rich, velvety texture and delicate, almost
buttery taste. Cooking maguro (and the toro in particular) is
considered by some to be a complete waste of a beautiful piece of
fish, as cooking significantly changes both the taste and texture of
You can get a good look at several varieties of tuna here:
NEFSC Fish FAQ
...and you can read about canned tuna and mercury levels here:
High mercury levels found in canned tuna
For more information about sushi, you might find these of interest:
Sticky Rice - For People Who Eat Sushi
My Sushi Chef
I hope this clears things up for you. If you need further assistance,
please just ask for clarification. I'll be happy to help!
Search terms: [ kinds of tuna ] and personal knowledge.