Common gambusia

Japanese: カダヤシ - かだやし(英語表記)common gambusia
Common gambusia

This freshwater fish belongs to the order Corbiculatus and family Guppyidae. It can live in brackish waters. It was once called tap minnow, but this name is now used for other groups of fish. It is native to the Atlantic coast of North America from New Jersey to Mexico, but has been introduced and established in over 50 countries around the world. It was introduced to Japan in 1916 (Taisho 5), and its distribution has been steadily expanding, and it has been recorded in Honshu south of Fukushima and Toyama prefectures, Shikoku, Kyushu, and the Ryukyu Islands.

They are often found in the lower reaches of rivers and shallow ponds. They can withstand water temperatures ranging from freezing to about 40°C, and as they are surface dwellers, they are resistant to oxygen deficiency in the water. They are ovoviviparous, giving birth to several dozen to 200 fry approximately every month during the breeding season from March to October. The male's anal fin has been modified into a rod-shaped copulatory organ. They feed on all kinds of small plants and animals, including diatoms and water fleas, but they tend to particularly prefer mosquito larvae (mosquito larvae) and pupae (giant mosquito larvae), fish eggs, and small fish.

The name "Kidayasi" means "to exterminate mosquitoes," and because of this characteristic, they have been introduced to many parts of the world, especially to areas with high rates of malaria. However, because they prey on fish eggs and larvae, there have been cases where they have caused great damage to native species in the areas they were introduced to, leading to their extinction. In Japan, they have caused significant damage to the killifish, which has a similar ecology. For example, in ponds and marshes in Tokyo and its suburbs, killifish have been driven out by the mosquitofish and are now almost nonexistent.

[Nobuhiko Mizuno]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

硬骨魚綱トウゴロイワシ目グッピー科に属する淡水魚。汽水域にも生息が可能である。タップミノーとよばれたこともあるが、現在ではこの英名はほかのグループの魚に用いられている。ニュー・ジャージーからメキシコにかけての北アメリカ大西洋側が原産地であるが、現在までに世界の50か国以上に移入され定着している。日本への移入は1916年(大正5)以来で、分布域を確実に拡大しており、最近までに福島県・富山県以南の本州と四国、九州、琉球(りゅうきゅう)諸島各地で記録されている。

 川の下流域や浅い池に多く生息する。結氷から約40℃までの水温に耐えることが可能なうえに、水面生活者であるため水中の酸素欠乏に強い。卵胎生で、3~10月の繁殖期にはほぼ1か月置きに数十尾から200尾の仔魚(しぎょ)を産む。雄の臀(しり)びれは棒状の交尾器に変形している。珪藻(けいそう)やミジンコをはじめあらゆる小形の動植物を食うが、とくにカの幼虫(ボウフラ)と蛹(さなぎ)(オニボウフラ)および魚卵や小魚を好む傾向がある。

 名のカダヤシは「蚊絶やし」を意味しており、この特性を買われて、世界各地とくにマラリアの多発地帯に移入された。しかし、魚卵と仔魚を食害するため、移入先の土着種に大被害を与えて絶滅させた例もある。日本では生態の類似しているメダカの被害が著しい。たとえば、東京都内とその近郊の池沼では、カダヤシに駆逐されてメダカはほとんどみられなくなった。

[水野信彦]

出典 小学館 日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について 情報 | 凡例

<<:  Katayamagai (Seashellfish) - Katayamagai

>>:  Alvise da Ca'da Mosto

Recommend

Gribeauval, JB (English spelling) GribeauvalJB

…It was during this period that the idea of ​​exp...

Ketaka [town] - Ketaka

A former town in Kedaka District facing the Sea of...

Galactic X-ray - ginga x-ray (English spelling)

In 1962-63, it was discovered that strong X-rays a...

Nummulites

A group of macroforaminifera (higher foraminifera...

"Song of the Kanto Partisans"

…In 1931, he published the anti-war poem "Li...

Engelhorn, F.

…The company was founded in 1861 in Mannheim by F...

Training camp - Gashuku

〘noun〙① A group of people staying together in the ...

Japan Productivity Center

A public interest incorporated foundation whose p...

Elevator - elevator (English spelling)

An elevator that moves a cage carrying people or ...

Khālsā (English spelling) Khalsa

…After his father, Tegh Bahadur, was captured and...

Andreas

...One of the musical pieces, "The Woman Wit...

Kichiji the Gold Seller

A legendary figure known for the Yoshitsune legend...

chaperon

...This is said to reflect the shape of the spire...

Binary star

A binary system is a system in which two stars ar...

Kaiseki Matsumura

A religious leader and the head of the Dokai (Way...