A depiction of Kun
Kun (Chinese: 鯤/鲲), also known as Gon in Korean, is a giant fish or whale in Chinese and East Asian mythology. In the Zhuangzi, Kun is described as an mythological creature in the Northern Sea whose size is immeasurably enormous. Kun transforms into the giant bird, Peng.
The Zhuangzi[]
In Chinese literature, the Daoist classic Zhuangzi has the oldest record of the Kun-Peng myth. The kun-Peng myth is believed to be the "central myth" of the Zhuangzi by Robert Allinson and other scholars:
"In the northern darkness there is a fish and his name is K'un. The K'un is so huge I don't know how many thousand li he measures. He changes and becomes a bird whose name is P'eng."