Ariakehime icefish - Ariakehime icefish (English name)

A fish belonging to the order Salmoniformes, family Icefish. It is an endemic species of Japan that lives only in the tidal areas of the Chikugo River and Midori River, which flow into the Ariake Sea. Its body is transparent and has almost no scales. It can be distinguished from other icefish by the fact that males have 16-17 scales along the base of their anal fin, that mature males have one black spot at the base of their anal fin, that their pectoral fins are small with 22-26 fin rays, that they have no teeth on their palate, and that their body length is only about 6 cm. They spawn from March to June. They live for one year. The stock has been drastically reduced by dams, water intake, and gravel mining, and the Ministry of the Environment's Red List (2013) lists them as endangered, which means that there is a very high risk of extinction in the wild in the near future.

[Kunio Amano]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

硬骨魚綱サケ目シラウオ科に属する魚。有明海に注ぐ、筑後(ちくご)川と緑川の感潮域にのみ生息する日本の固有種。体は透明で、ほとんど鱗(うろこ)がない。雄の臀(しり)びれ基底に沿ってならぶ鱗は16～17枚であること、成熟した雄の臀びれ基底に1個の黒色斑(はん)があること、胸びれが小さく、その鰭条(きじょう)は22～26本であること、口蓋(こうがい)骨に歯がないこと、体長は6センチメートルほどにしかならないことなどでほかのシラウオ類と区別できる。産卵は3～6月。寿命は1年。ダム、取水、砂利採取などで資源量が激減し、環境省のレッド・リスト（2013）では近い将来野生絶滅の危険性がきわめて高い、絶滅危惧ⅠA類に指定されている。

［尼岡邦夫］

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