The idiom something smells fishy means that something is not on the up and up, something about a person or situation arouses suspicion. Until the mid-1800s, the word fishy merely referred to something that literally smelled of fish. Today, when something is referred to as smelling fishy, it usually means that a person or situation arouses suspicion or doubt. The origin of something smells fishy is shrouded, it is assumed that it is a reference to the unpleasant smell of fish past its prime. Related terms are something smelled fishy, something is smelling fishy.
Examples
Sample comment on Facebook from Raoul Martinez, a TV anchor in San Diego: “You guys buying this? I’m no conspiracy theorist, but this smells fishy to me.” (The Washington Post)
“It smells fishy. Kurds do not benefit from it. There is a hidden agenda,” he claimed. (The Daily Sabah)
But something smells fishy. (The Telegraph)
The selection process should be inclusive of local artists who want to create permanent works, which is why this high-dollar award smells fishy to me. (The Salt Lake City Weekly)
Why You Shouldn’t Trust Dr. Oz’s Latest Fishy Propaganda (Forbes)
There is, in general, something rather fishy about most claims regarding the single best way to eat. (The Huffington Post)
But there’s something fishy going on. (The Business Insider)
“I have always suspected something fishy since his milk is very light,” said John Opiyo the trader. (Kisumu County News)
Accusing the BJP of foul play, Congress Corporator Mohsin Haider said: “It is fishy how urgently the BJP wants this proposal to be passed.” (The Free Press Journal)
After sensing something fishy, she immediately asked the driver to pull over and when he refused, she had to jump out of the taxi. (The Malaysian Digest)