Yesterday I used this idiom in my post, and then got wondering about it’s origin. Why would this phrase come to mean a completely different situation, and more importantly, who would put fish in a kettle in the first place?

Well first of all, a fish kettle is not the same as a common modern kettle used for boiling water for a nice cup of tea. It was a long dish used for cooking (mainly poaching) whole fish. They’re still used today by some chefs, but a modern fish kettle is a whole other… thing, compared to 19th and 18th century ones, which were big, heavy, solid objects.

It seems that a kettle of fish first came to generally refer to a muddled or confused state of affairs, used in sentences such as This is a fine kettle of fish we’re in. Why the phrase might come to be used in this way is not immediately apparent. Maybe it referred to the mess of bones and skin and fish heads left behind in the kettle after the fish had been eaten. Whatever the reason, it had entered fairly common usage by the end of the 18th century, and it wasn’t a great leap to go from a kettle of fish in general, to a whole other/new kettle of fish to refer to an entirely different set of affairs. It was quite common by the middle of the 19th century, with some suggesting it was inspired by the American-English expression a whole other ball game.

A kettle of fish is, like most idioms, a tricky thing to learn if you’re not a native speaker. The issue with idioms is that they’re usually so apparently divorced from their meaning. Imagine you presented an English learner with the phrase without context, and asked them to figure out what it means. Even in cases like this where there’s an origin for the term, it doesn’t really clear things up, and could you imagine explaining all the above in a classroom? Idioms are a great way to make your English sound natural, but it’s worth keeping in mind how common they are and how easy they are to understand if you’re speaking with a non-native speaker. There’s a good chance they haven’t come across it, and the meaning might be very hard to divine, especially if it’s one only used in a certain country or region. I had this experience recently with the French idiom se mettre sur son 31. I tried to figure out what it could mean, but to no avail, so I looked it up and discovered its closest English equivalent would be dressed up to the nines. I still couldn’t see the link between the phrase and its meaning though, until I learned that the 31 refers to 31 December, so the phrase means to dress as you would on New Year’s Eve. If you were French.

Still, the difficulties of idioms can also be quite useful too. The simple fact that they can seem so different from what they refer to, and often feature unusual but memorable images (a tea kettle filled with fish, for example) also makes them more likely to stick in someone’s mind. I’ll never forget se metre sur son 31. But getting to the point where you can use idioms confidently and in their appropriate context in another language? Well, that’s a whole other kettle of fish!