In Canada, and presumably the rest of the world, we simply say “tuna,” 'cause, like we know it’s a fish. So, why “tuna fish” in the U.S? It’s not like you say “chicken bird,” or “pork chop pig,” or anything. What gives?
Because it allows us to trot out the old line “You can tune a piano, but you can’t tuna fish.”
Other than that, no idea.
Curse you Mr. Rosewater for beating me to that!
In Thai, everything – including sharks and squid – is such-and-such fish (or fish such-and-such, since fish – “pla” – is placed before the type it is.
Oddly, they have ham here, and while pork has long been eaten, ham itself is fairly recent and considered a Western delicacy. It is without fail called “mu ham,” or “pig ham” (“mu” means pig and pork both. It’s pronounced like we say “moo,” as in what a cow says. That leads to no end of mirth when you first get here and learn it. Then you get over it.)
And a damned fine REO Speedwagon album it was…
Of course you can tuna fish. Otherwise it would go bad sitting on my shelf.
…and why Buffalo wings
…Because they were first popular in Buffalo, New York.
But why’s it called “Chicken by the Sea”? Or is it “in the Sea”? I forget. Anyway, I know it’s tuna, but it says “chicken”.
It’s Chicken of the Sea.
That’s a StarKist® Tuna trademark “Chicken of the sea.”
Starkist and Chicken Of The Sea are competitors.
As a Brit how the hell was I expected to know that 
You ask the dope, of course.
oh, and BTW I usually just say tuna
- Tuna Sandwich
- Tuna Fish Sandwich
?
To totally pull something from my behind, I’ll guess that tuna (for sandwiches) is sold in cans and that the most popular brand was labeled “Tuna Fish”. I base that on exactly no knowledge given as I don’t eat tuna and have never bought a can of it. I do call it tuna unless talking about a sandwich though.
That really is a gross image.
It’s context dependent, isn’t it? If someone asks “so what kind of fish is ‘ahi’?” I think most Americans would answer “it’s yellowfina tuna,” not “it’s yellowfin tuna fish.”
In everyday usage, I think it has to do with meter. “What’s for lunch?”
“Tuna” … just kind of trails off.
“Tuna fish” has two beats, at least. (I guess those would be “feet,” in poetry-talk, but I’m not going to pretend I remember any of that stuff from high school English class.)
Think about it: you can say “tuna fish sandwich” or “tuna sandwich,” and either one falls fine on the ear, but did you ever hear anyone talk about a “tuna fish noodle casserole”? Heck, no. A “tuna noodle casserole” has four nice beats to it.
Seems to me that the word ‘fish’ after tuna is superflous to requirements.
You can hardly have a tuna chicken salad can you?
A tuna AND chicken yes
snerk 
:smack:
“Pizza pie” is the one that still looks odd to my eyes.
Still, I guess it’s not uncommon. A lot of languages seem to say things like “red colour”, or “pork meat”.