In Japan, folklore says that uncommon appearances of deep‐sea fish are an earthquake precursor. If this folklore is proved to be true, the appearance of deep‐sea fish could be useful information for disaster mitigation. However, a statistical survey has not been conducted on this subject because a database of such information had yet to be compiled. In Japanese domestic local newspapers, such appearances have often been reported because rare appearances might attract readers. The authors constructed a database of reports from newspapers, academic articles, and the marine museum. In this study, fish species generally implicated in earthquakes, such as oarfish and slender ribbonfish, were the focus. Although the catalog used might not include all of the events of deep‐sea fish appearances around Japan because of a lack of whole coverage observation, the earthquake occurrence rate after deep‐sea fish appearances can be evaluated. Thus, the usefulness of the deep‐sea fish appearance information for disaster mitigation was evaluated. From this investigation, the spatiotemporal relationship between deep‐sea fish appearances and earthquakes was hardly found. Hence, this Japanese folklore is deemed to be a superstition attributed to the illusory correlation between the two events.