Cold fish

What is the origin of the idiom "cold fishing" and when to use it?

The idiom "cold fish" has its roots in the early 20th century and it likely stems from the association of fish with cold-blooded animals that do not exhibit warm emotions or expressions. It is used to describe someone who seems unfeeling, aloof, or indifferent, often making it difficult for others to form a close or emotional connection with them.