Tokyo bitterling

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Tokyo bitterling
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus: Tanakia
T. tanago
Binomial name
Tanakia tanago
S. Tanaka, 1909
  • Rhodeus tanago Tanaka, 1909
  • Pseudorhodeus tanago Tanaka, 1909

The Tokyo bitterling (Tanakia tanago) is a temperate freshwater fish of the carp family (Cyprinidae). Taxonomically, it belongs to the subfamily Acheilognathinae.

The species was first described as Rhodeus tanago by Shigeho Tanaka in 1909. It is widely known as Tanakia tanago,[2] although a 2014 study suggests it is genetically distinct from other Tanakia species, and warrants placement it the monotypic genus Pseudorhodeus.[3]


In the wild, this fish is found only on the Kantō Plain of Japan, an area near the capital city, Tokyo. The fish was formerly abundant in small streams, but its habitat has been overrun by people and pollution.


There is a real risk that it could become extinct in the wild. It also suffers from competition from the related but more aggressive rosy bitterling. Bitterlings lay their eggs in freshwater mussel shells. The Tokyo bitterling lays its eggs in only one type of mussel shell, limiting its chances of successful breeding. To help protect the fish, it has been declared a "national monument" by the Japanese government, and this gives it special protection.[citation needed]


  1. ^ Hasegawa, K., Kanao, S., Miyazaki, Y., Mukai, T., Nakajima, J., Takaku, K. & Taniguchi, Y. 2019. Tanakia tanago. The IUCN Red List of Threatened Species 2019: e.T21383A110464790. Downloaded on 25 July 2019.
  2. ^ Tanakia tanago. Catalog of Fishes. California Academy of Sciences Archived 2014-10-06 at the Wayback Machine. 27 August 2014. accessed 4 Oct 2014
  3. ^ Chang, C.-H.; Li, F.; Shao, K.-T.; Lin, Y.-S.; Morosawa, T.; Kim, S.; Koo, H.; Kim, W.; Lee, J.-S.; He, S.; Smith, C.; Reichard, M.; Miya, M.; Sado, T.; Uehara, K.; Lavoué, S.; Chen, W.-J. & Mayden, R.L. (2014). "Phylogenetic relationships of Acheilognathidae (Cypriniformes: Cyprinoidea) as revealed from evidence of both nuclear and mitochondrial gene sequence variation: Evidence for necessary taxonomic revision in the family and the identification of cryptic species". Molecular Phylogenetics and Evolution. 81: 182–194. doi:10.1016/j.ympev.2014.08.026. PMID 25238947.