What joke is there a fish in the North Ghost?

There is a kind of fish named Kun in the north. Kun is so big, I don't know its thousands of miles; Become a bird. Its name is Peng. Peng's back is thousands of miles away; Fly away angrily, its wings hang in the sky like clouds. If it is a bird, shipping will migrate to Nanming, and Nanming is Tianchi. "Qi Xie", ambition is strange. The text of "Hehe" says: "Peng moved to Nanming, and the water hit three thousand miles. It was Jiu Wan Li who climbed up and went to rest in June. "

From Zhuangzi's "Happy Travel"