fish out of water, a

Idioms  

1. A person away from his or her usual environment or activities. For example, Using a computer for the first time, Carl felt like a fish out of water, or On a hiking trail, Nell was a fish out of water. This expression alludes to the fact that fish cannot survive for long on dry land. [Late 1300s]

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Example Sentences

Once the scheme is set up, keeping it up falls to Robert, the fish out of water, a rube in a den of minxes.

From Washington Post

If a sailor on land is a fish out of water, a soldier at sea is like a game cock in a duckpond.

From Gallipoli Diary, Volume 2 by Hamilton, Ian, Sir