chéng mén shhüu，yāng jí chí yú
[Interpretation] The city gate was on fire, and everyone went to the moat to get water. When the water ran out, the fish died. Metaphor suffers losses or disasters because of being implicated.
[Language] Du Fu of the Northern Qi Dynasty wrote for the Eastern Wei Dynasty: "I am afraid that Chu will die and Lin Chi will be late; There is a fire at the city gate, which affects the fish in the pool. "
Chengmen fish disaster