earlier this year hsbc chief economic analyst stephen king observed that while tunisia and egypt hold little relevance for the oil market, libya is a different kettle of fish that accounts for around 2 percent of total global output.
not that stephen king
worldwide words says
There are actually two common idioms based around the phrase a kettle of fish. One means “This is a different matter from the one previously mentioned” (like the libya example above). The other is more of an exclamation: either as a pretty kettle of fish! or a fine kettle of fish!, meaning that some awkward state of affairs has arisen.
a kettle of fish was the title of this forgotten movie starring gina gershon and matthew modine, whose character is dealing with a figurative kettle of fish that is a result of his messy love life and odd roommate.
kettle of fish is a greatest hits compilation by the band fish
fine kettle of fish is commonly used as a pun in the name of seafood restaurants and catering services, like this one in niagara falls, ontario.
another idiom that uses fish and a container is like shooting fish in a barrel, which indicates that something is easy.
a kettle of fish (left) and a fish in a barrel
in this vid the mythbusters confirmed that shooting a fish in a barrel is indeed pretty easy