This is one of the many 'Catfish Pictures' that were painted following the Great Earthquake of Ansei. The popularity of 'Catfish Pictures' spread quickly among the people who used it is a talisman to guard the body against earthquakes or as an incantation to dispel anxiety.

As it was believed that earthquakes were caused by catfish inside the earth moving about, after the Ansei Earthquake a great amount of 'Catfish Pictures' featuring caricatures of catfishes were published and proved to be very popular with the people.
The tenth month of the lunar calendar when the earthquake struck was called Kanna-zuki which means the month where the gods are absent as it was believed that during this month all the Shinto deities gathered around Izumo. It is assumed that the figure reclining on the keystone erected in Kashima Shrine in Ibaraki Prefecture as a measure against earthquakes is Ebisu who took care of the area during the absence of other gods, and it likely represents how the catfish jolted around while he was having a snooze. The Kashima Daimyojin who daily presses down on the catfish with the keystone is also pictured hastening a horse as if saying "I must go quickly to sort it out"