“Bigger fish to fry” is a colloquial expression in American or British English that generally means someone has more important things to do than what is currently being done or proposed by someone. The phrase is one of many idiomatic expressions in the English language that is composed of words that together can have an unpredictable meaning from what they seem to mean. Related idioms include “other fish to fry” and “small fry.”
Both common variants on the idiom also refer to someone who feels he or she has more important things to do with his or her time, or who is busy and cannot be bothered by current problems. The idiom “small fry” can also have a dual meaning. It literally can be interpreted to mean “little fish,” as well as having the connotation that it refers to minor or unimportant matters, as in "smaller fish to fry."
The origin of the phrase “bigger fish to fry” and its related idioms is lost to antiquity, but it is a well-known phrase in both Irish and British culture. The first known reference of it in writing, when it was likely already widespread, was in The Memoirs, written by English writer and gardener John Evelyn in 1660. The Memoirs was a collection of diaries in which Evelyn discussed the culture and politics of his day.
Other languages have their own variations on this phrase. The French idiom most closely related to it translates to “He has many other dogs to whip.” The version conveyed by the Spanish novelist Miguel de Cervantes in the two volumes of Don Quixote de la Mancha, published in 1605 and 1615, was “other things on which to think.” When Peter Anthony Motteux, a English author famous for his translations, translated Don Quixote into a four-volume 1712 edition, he rendered Cervante's original phrase as “I have other fish to fry.”
There are so many idioms in the English language, with some sources claiming anywhere from 1,600 to 3,500 of them in regular use, that it can be a difficult language to master. Over 130 such phrases are said to have been invented by William Shakespeare alone. Many English idioms also have their origins in other languages such as Latin, Greek, French, and German. The origin of “bigger fish to fry” may never be known, but idioms like it that have a catchy alliteration and make reference to common objects may be with us for a long time to come.