Crayfish in Japan
In Japan, three species, Cambaroides japonicus, Procambarus clarkii and Pacifastacus leniusculus/trawbridgii are to be observed in wild life. Cambaroides japonicus is solely indigenous and other two species has emigrated from North America less than a century ago.
Cambaroides japonicus
This uniquely indigenous crayfish is called "Nippon zarigani" which means "Japanese crayfish" in Japanese. "Japanese crayfish" is native in northern area, Hokkaido and Touhoku, where "Japanese crayfish" lives in a clean and cool water creek of low water temperature well below 20 C. "Japanese crayfish" is not tolerant of higher temperature and degraded water quality, and therefore cooler system and powerful filtration are required to keep "Japanese crayfish" in Tokyo, especially in its muggy summer. Though "Japanese crayfish" are sold (in retail price of around \3000 or US$30 in Tokyo) in aquarium shops during winter, this species is reportedly on the way to extinction. "Japanese crayfish's" appearance and size (5 to 8cm or 2 to 3 inches) dose not necessarily attract crayfish keepers but its rareness seems to attract them. "Japanese crayfish" used to be caught for food or traditional medicine. The gastrolith, stomach stone, had been actually handled as a sort of traditional medicine. But nowadays because of development and its destruction of habitat circumstance, the number of "Japanese crayfish" has steadily declined, and some local governments declared "Japanese crayfish" as an endangered species.
Procambarus clarkii
Procambarus clarkii, known as red swamp crayfish, is predominant in major islands in Japan. This species is imported from North America in 1920's, and since then, the number of Procambarus clarkii has exploded because of its high tolerance and freedom from predators. Procambarus clarkii can be observed naturally in most ponds, swamps and rivers in three major islands, Honsyu, Shikoku and Kyuusyu, and it is now invading even to Hokkaido.
Procambarus clarkii is called "America zarigani" which means "American crayfish" in Japanese. "American crayfish", especially reddish one, is popular among kids as a pet because of its easiness to access and to keep. Majority of Japanese male must have their memory that they had been crazy about catching "American crayfish" in their childhood. Though Procambarus clarkii is aquacultured in North America or Europe, quite a few people eat it in Japan. Aquarium shops sell "American crayfish" not only for pets but also for feed for large carnivorous fish. (Retail price is less than \100 or US$1.) These days, albino or blue type of Procambarus clarkii was made and handled in aquarium shops in higher price (of more than \3000 or US$30).

Pacifastacus leniusculus/trawbridgii
Pacifastacus leniusculus/trawbridgii living in Japan is called "Tankai/Uchida crayfish". This crayfish was originally imported from North America like "American crayfish" for farming in 1920's or 1930's, and now lives naturally in Hokkaido, Ishikawa , and Tankai Lake in Shiga in Honsyu. "Tankai/Uchida crayfish", Pacifastacus leniusculus/trawbrigii, is good for food because of its high proportion of tail meat. In addition, it attracts crayfish keepers because of its larger size than "Japanese crayfish" and "American crayfish" and its robust appearance in spite of mediocre brown color. "Tankai/Uchida crayfish" lives in cool water and, therefore, the cooler system is needed to keep it in Tokyo in summer. Retail price in aquarium shops in Tokyo is around \3000 or US$30.
However, in Febraury 2006, Pacifastacus leniusculus were totally banned by the Special Alien Animal Law which imposes a violator the punishment of no more than three-year-imprisonment. Ministry of Environment is making efforts to eliminate Pacifastacus leniusculus from the ponds, reivers, and lakes in Japan
Other crayfishes
Yabby, Red Claw, Marron and other imported crayfish had been becoming popular among aquarium lovers. Actually more and more Yabbies, Red Claws and Marrons were imported and sold in aquarium shops. Blue colored animals were higher valued and sold in higher price. They were kept under artificial circumstances and are reported not to be seen in natural places in Japan. Yabby has, however, potential to be a new habitant in wild life in Japan because of its tolerance on temperature and water quality. Competitiveness with first comer, "American crayfish", may hamper its prevalence. Marron and Red Claw do not seem to have potential to be habitant in Japan except some particular areas because of their intolerance on high temperature and low temperature respectively.
In Febraury 2006, all the Australian crayfish were also totally banned by the Special Alien Animal Law which imposes a violator the punishment of no more than three-year-imprisonment.