Fish head soup is an important clue in Happy Mom. In the play, Xia Feifei lost her memory, only remembering that she likes to drink fish head soup. When she was a child, she always drank fish head soup cooked at home on her birthday every year, but she didn't remember anything about her family. Sun Yi, the chairman of the group, and Sun Xiaofang, the favorite daughter of his wife Liu Wanhua, lost their lives when they were 9 years old. The husband and wife searched for their children for decades but failed to find them. Liu Wanhua cooks fish head soup for her daughter on her birthday every year.

In episodes 5 1 and 52, Xia Feifei and Liu Wanhua meet in the market because they buy fish heads. Xia Feifei said that she likes to drink fish head soup on her birthday, and Liu Wanhua also thinks that it is a coincidence that her daughters Xiao Fang and Xia Feifei are still in the same studio and both like to drink fish head soup. Fei-fei xia gave Liu Wanhua the last fish.

Finally, the mother and daughter met.