kettle of fish, a fine/pretty

kettle of fish

1. Also, a fine or pretty kettle of fish . An unpleasant or messy predicament, as in They haven't spoken in years, and they're assigned to adjoining seats-that's a fine kettle of fish . This term alludes to the Scottish riverside picnic called kettle of fish, where freshly caught salmon were boiled and eaten out of hand. [Early 1700s]
2. a different or another kettle of fish . A very different matter or issue, not necessarily a bad one. For example, They're paying for the meal? That's a different kettle of fish. [First half of 1900s]
See also: fish, kettle, of

a pretty kettle of fish

or

a fine kettle of fish

BRITISH, OLD-FASHIONED
If you describe a situation as a pretty kettle of fish or a fine kettle of fish, you mean that it is difficult or unpleasant. Well, this is a pretty kettle of fish, as Queen Mary said. Note: `Kettle' in these expressions may come from `kiddle'. Kiddles were baskets or nets which were laid in streams and rivers to catch fish. Alternatively, `kettle' may refer to a fish kettle, which is a long narrow saucepan that is used for cooking fish.
See also: fish, kettle, of, pretty

a pretty (or fine) kettle of fish

an awkward state of affairs. informal
In late 18th-century Scotland, a kettle of fish was a large saucepan of fish, typically freshly caught salmon, cooked at Scottish picnics, and the term was also applied to the picnic itself. By the mid 18th century, the novelist Henry Fielding was using the phrase to mean ‘a muddle’.
See also: fish, kettle, of, pretty

kettle of fish, a fine/pretty

A messy predicament. This term is believed to come from a Scottish custom of holding a riverside picnic, itself called a “kettle of fish,” where freshly caught live salmon are thrown into a kettle boiling over an open fire and then are eaten out of hand, definitely a messy procedure. Sir Walter Scott described just such a picnic in St. Ronan’s Well (1824), but the transfer to other kinds of messy predicament had already occurred in the early eighteenth century. The term appears in Henry Fielding’s Joseph Andrews (1742) and works by Dickens, Hardy, Shaw, and many others, but it may now be dying out, at least in America.
See also: fine, kettle, of, pretty