In 1927, Japan imported about 100 Louisiana crayfish to feed farmed bullfrogs, only 20 survived and their descendants later spread to every prefecture except Hokkaido

The red swamp crayfish has become a familiar sight in Japan, particularly around ponds, irrigation channels, and rice fields. It is now widespread in the country's rice-growing areas, particularly where established populations have taken hold. Much of Japan's red swamp crayfish population traces its origins to a shipment of roughly 100 crayfish brought to the country in 1927 for a single purpose: feeding another imported animal that Japan was trying to farm for profit.