The Chinese idiom 如魚得水 (rú yú dé shuǐ), literally “like a fish that has found water,” is a metaphor that describes finding an acquaintance whose disposition, interests, or outlook is highly similar to one’s own, or being in a very suitable or agreeable environment.
The idiom originated from a story about famous strategist Zhuge Liang (also named Kong Ming) and his lord Liu Bei in the historical text “Records of the Three Kingdoms,” which covers the history of China’s late Eastern Han Dynasty (A.D. 184–220) and Three Kingdoms Period (A.D. 220–280).