Why is origin unknown for "shooting fish in a barrel"?

AFAIK, even etymology experts can’t say for certain* the origin of the phrase “like shooting fish in a barrel” as a simile for for something incredibly easy. Why is the origin of this particular phrase so hard to pin down (compared to the rest)?

*or as certain as they are about other common idioms and words.

It’s not even quite clear what the phrase means. It is easiest to picture live fish, for some reason, swimming in a barrel, and somebody inexplicably shooting at them. That would be an impractical, unnecessarily dangerous way of getting at the fish.

It could mean firing a gun into which you have dropped a fish or two.

It could mean shooting fish into a barrel.

It could even mean “fish” as the con-man’s word for his victims.

Good grief, this is getting boring, even to me.

Are you under the impression that we know the origins of nearly all phrases? Lots are of unknown or unconfirmed origin - it’s not clear that “shooting fish in a barrel” is an outlier.

Most likely, the image is that of a barrel filled with fish and ice, which was how they were shipped. No way you could miss if you shot into that.

But there are many phrases that have no clear origin. Try looking up “rule of thumb” or “the whole nine yards.” Hell, no one is exactly sure the etymology of the word “bird.”* The majority of phrases and words have a clear etymology, but there are a large number of them that are no more than speculation.
*The anglo-saxon word is “fowle” and there was “brid,” meaning “brood,” but no one knows how that changed to “bird” – of if it actually did.

They tried it on Mythbusters. They constructed a fake, mechanical fish for the kind-hearted viewers. They had it swim in a barrel then shot at it with various weapons. Turned out that if you’re using a pistol, what with the way water bends light, it’s harder than one might think. It’s pretty easy with a shotgun, though.

We all forgot.

Lenny was supposed to remember, but you can’t trust him with anything.

There are two things you have to do when fishing with a rod and reel. First, you have to get the hook in front of a fish. Every fisherman has spent time trying to figure out where the fish are/where they should cast, and has likely thought something like “man, if only I could see the fish right at my feet and just dangle the bait right in front of them.” Second, you have to convince the fish to take the hook. It’s a singularly frustrating and somewhat common experience to fish in a stream that’s teeming with fish that just refuse to bite.

The phrase solves the two difficulties of fishing: you don’t have to find the fish, they’re right there in front of you and can’t escape. And you don’t have to convince them to take your lure, you can just blast them out of the water.

I was puzzled as to why they treated it as a live fish and a lot of water in a barrel.

Caught fish “back when” were regularly moved about in barrels. Packed tight and all that. Little to no water. It would be impossible to miss shooting directly into the barrel, hence the meaning. The sentence structure even seems to imply that “fish” means the plural. Not “… a fish in a barrel.”

I know nothing about the phrase but I have literally shot fish in a barrel. If we caught a surplus in a net we would put them in a barrel of water. Later when a fish fry was planned we would just shoot into the barrel. The concussion would daze the fish and they could just be picked out by hand.

“Getting all your ducks in a row” is equally obscure.

This is typical of Mythbusters: defining the problem in a way that has nothing to do with the reality of what they’re trying to prove. They very often don’t disprove myths; they created a simulation of they myth, but changed enough to make their “proof” useless. It’s “Let’s prove or disprove A, by doing B, which vaguely resembles A.”

The only way fish would be in a barrel would be if it were filled with fish, along with ice, in order to ship it. This was how oysters were shipped in the 19th century; you could get the oysters from New York to Chicago and they’d still be safe and edible.

The barrel would be packed with as much fish as you could fit in, with just enough ice to keep it cold. It wouldn’t be difficult at all to hit a fish in that condition: you hit the barrel, you hit a fish.

They were testing the idiom. I think most people imagine shooting fish in a barrel as a bunch of fish swimming in a barrel, not a barrel packed full of ice and fish.

How do you keep the water from leaking out through the bullet holes?

Look for a UK documentary series called Balderdash and Piffle. Victoria Coren goes around trying to determine earlier evidence of certain words being used, to help out the Oxford English Dictionary. You learn a bit about etymology, history, and how dictionaries are compiled, as well as just being entertaining.

Why would they think that? It does not make sense. Trying to shoot a single fish swimming in a barrel would be hard. On the other hand, shooting a fish in a barrel full of fishes would be easy, which is the point of the idiom.

I’ve always pictured it as a barrel full of water with lots of fish in it. The “easy” part is that there are a lot of fish and they’re contained in the barrel, with no place safe to hide.

It’s “shooting fish in a barrel,” not “shooting a fish in a barrel.” Picture a 55 gallon drum with about two dozen 5-10 lb bass in it. Now picture blasting away at it with a gun. Even if you miss the first time, it’s pretty easy to pull a trigger 9 or 10 times.

Once again, I repeat, I’ve no idea where the phrase came from but I’ve done it. [It is a controlled variation of what Wikipedia calls blast fishing.] One does not have to blast away multiple times. The concussion from the first shot will daze the fish. It will tend to list to one side and tend to float. One can pick it up by hand.