Ku Yu Zhi Si (The desperate struggle of fish)
During the Warring States Period, Zhangzi's family was very poor. When they had nothing left to eat, Zhangzi went to borrow some money from a local official. However, the official told Zhangzi that he would not be able to lend him any money until after he had collected the rent.
Zhangzi was very angry, and he said to the official, "Yesterday I saw a crucian carp in a ditch that had dried up.He looked as if he was about to die, and asked me to quickly fetch a bucket of water to save his life. I told him that I was on my way south, where there is a lot of water, and that I would certainly bring some back for him. But the carp grew very angry and said,
"By the time you've gotten back with that water, I won't be here anymore! You'll have to go look for me at a dried fish store!"
This idiom is used to mean that a promise of help later is of no use in an immediate crisis.