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Gambusia affinis

Basic information
Scientific name Gambusia affinis

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Common names Mosquitofish, Topminnor
Higher taxon Poeciliidae, Cyprinodontiformes, Actinopterygii
Natural range USA (Mississippi River) to N Mexico
Habitat Slow streams, canals irrigation. Tolerant to high salinity and water pollution. Do not require aquatic grass for oviposition.
Invasion information
Range in Japan Fukushima Pref. and southern part of Honshu, Shikoku, Kyushu, Okinawa, and Ogasawara Islands. Range in Japan
Origin Taiwan
Date The first introduction was in 1916 to Nara Pref. Since 1970, distributed throughout Japan.
Route Deliberate: Control of mosquito.
Impact Competition with Medaka (Oryzias latipes). Predation on juvenile Medaka.
Native organism(s) affected: Medaka Oryzias latipes
Regulation in Japan Import, transport and keeping are prohibited by the Invasive Alien Species Act.
Introduced range in other countries Worldwide, including many small Pacific islands.
Reference Notes
  • DECO (ed) (2006) Dictionary of Alien Species. Tokyo-Shoseki, Tokyo (in Jpn)
  • Ecol Soc Jpn (ed) (2002) Handbook of Alien Species in Japan. Chijinshokan, Tokyo (in Jpn)
  • Froese & Pauly (eds) (2009) FishBase (Accessed on 2010-12-10)
  • JWRC (ed) (2008) A Photographic Guide to the Invasive Alien Species in Japan. Heibonsha, Tokyo (in Jpn)
  • Kawanabe et al. (eds) (2002) Freshwater Fishes of Japan, 3rd ed.. Yama-kei Publishers, Tokyo (in Jpn)
  • Matsuzawa & Senou (2008) Alien fishes of Japan. Bun-ichi Sogo Shuppan, Tokyo (in Jpn)
  • etc.
100 of the World’s Worst Invasive Alien Species and 100 of the Japan’s Worst Invasive Alien Species.