如鱼得水 — “To be in one's element”

The idiom "Ru Yu De Shui" (如鱼得水) originates from "Records of the Three Kingdoms, Book of Shu, Biography of Zhuge Liang." It compares someone to a fish finding water, symbolizing finding a highly compatible person or a very suitable environment.

During the chaotic Eastern Han Dynasty, Liu Bei, determined to unify the land, sought out talented individuals. He made three visits to Zhuge Liang, who was living in seclusion at Longzhong, before finally meeting him. Liu Bei expressed his aspirations, and Zhuge Liang outlined a strategic plan involving taking Jingzhou and Yizhou, befriending southwestern ethnic groups, allying with Sun Quan, and campaigning against Cao Cao, predicting a tripartite division of the empire among Shu, Wei, and Wu. Delighted, Liu Bei appointed Zhuge Liang as his military advisor.

Zhuge Liang diligently assisted Liu Bei, but Liu Bei's deep trust and reliance on him caused displeasure among generals like Guan Yu and Zhang Fei. They often showed their dissatisfaction, with the straightforward Zhang Fei being particularly grumbling. Liu Bei patiently explained, comparing himself to a fish and Zhuge Liang to water, emphasizing Zhuge Liang's crucial intellect and courage for achieving his grand endeavor. He said, "My having Kongming is like a fish having water. I hope all of you will not speak of this matter again." Guan Yu and Zhang Fei then ceased their complaints.