This means that something feels wrong in a way that isn’t completely obvious, something suspicious, doubtful, or questionable.
‘Fishy,’ in the sense of ‘shady’ or ‘questionable’ was first recorded about 1840, perhaps from the notion of ‘slipperiness,’ or of giving off a bad odor. So it may refer to the fact that fish cannot be trusted not to slip out of your hands, or it may refer to the fact that they tend smell very bad when they go rotten.
‘Slippery as a fish’ has also been used to express disfavor. People have remarked on ‘fishy eyes’ to describe what they think of as dead-looking or staring eyes. A transaction that seems dishonest in some way is thought of as malodorous, and there’s no bad smell more noticeable than the smell of decaying fish. The current comment about something that is bad, whether it’s an investment, an event, or food, is ‘that stinks!’
However, there’s another story about the origin of the meaning of ‘fishy.’ In the nineteenth century, the connection between fish and bad investments arose in connection with one James D. Fish, a once-prominent New York banker. Fish was imprisoned for fraud subsequent to the Panic of 1884. That financial panic was led by the failure of Fish’s brokerage firm – in which Ulysses S. Grant had partnered – and the failure of the Marine National Bank, which Fish had headed.
How appropriate that someone named Fish should be head of the Marine National Bank! It reminds me of the small town I lived in years ago, where the local shoe store was owned by a Mr. Walkey.
Back to James D. Fish. More than 10,000 smaller firms also failed in the Panic of 1884. At that time very large numbers of speculators in the financial markets were punished for their adventures, thus Fish became a notorious figure when carted off to jail. Fish remained so on his release when he returned to live in seclusion in the library of his stately mansion on Twin Island, now Pelham, NY. While the antics of Fish the banker were not the source for ‘fishy,’ his imprisonment likely reinforced its usage in the USA.
Another theory is that it comes from the ‘fish stories’ of anglers who exaggerate the size of the ones they didn’t bring home.
And that’s my fish story for today!