What does the idiom fishy business mean?

"Fishy business" is an idiom that means suspicious or dishonest activity. It implies that something is not quite right, and that there may be something hidden or untrustworthy going on.

The idiom likely originated from the idea that fish are slippery and difficult to catch, and that fish markets were sometimes associated with shady dealings.

Here are some examples of how "fishy business" can be used:

* "I wouldn't trust that deal – it smells like fishy business to me."

* "The police are investigating the company for possible fishy business."

* "There's something fishy about the way he got that promotion."