a cold fish

cold fish

Someone who shows no emotion and comes across as unfriendly or disinterested. The manager decided not to hire Bill as the store greeter because he came across like a cold fish during the interview.
See also: cold, fish
Farlex Dictionary of Idioms.

a cold fish

If you call someone a cold fish, you mean that they do not show their emotions and can seem unfriendly or unsympathetic. Since the President is generally seen as a cold fish, it is all the more impressive when he does show his feelings. He didn't really show much emotion — he's a bit of a cold fish.
See also: cold, fish
Collins COBUILD Idioms Dictionary, 3rd ed.

a ˌcold ˈfish

(disapproving) a person who shows little or no emotion, or is unfriendly, reserved, etc: When I first met him, he seemed rather a cold fish, but actually he’s quite passionate.
See also: cold, fish
Farlex Partner Idioms Dictionary

cold fish, a

A person who is unfeeling, or at least shows no emotion. “Cooler than a fish on a cake of ice,” P. G. Wodehouse put it (Money in the Bank, 1942). He was scarcely the first. Shakespeare wrote, “It was thought she was a woman and was turned into a cold fish” (Autolycus telling of a ballad against the hard hearts of maids, The Winter’s Tale, 4.4). See also cold heart.
See also: cold
The Dictionary of Clichés by Christine Ammer
See also:
  • cold fish
  • cold fish, a
  • choked with emotion
  • breeze past (someone or something)
  • give (one) the cold shoulder
  • give someone the cold shoulder
  • he, she, etc. isn't having any
  • not be having any of it
  • not having any
  • be not having any (of it)