Ayu (Sweetfish)アユ

Plecoglossus altivelisLC— Least Concern

The ayu, or sweetfish, is a small East Asian fish known for its short annual life cycle: hatching in rivers, drifting to sea as larvae, and returning upstream in spring to graze on algae before spawning and dying in autumn. Prized in Japanese cuisine for its delicate melon-like aroma, it is fiercely territorial over the algae-covered rocks it feeds on, a trait exploited in traditional decoy fishing.

Ayu (Sweetfish) (reference photo)
Photo: OAS at Japanese Wikipedia / CC BY-SA 3.0 / Source / cropped

Species Data

Classification
Osmeriformes / Plecoglossidae Source
Distribution
Native to the northwestern Pacific coast of East Asia, ranging from Hokkaidō, Japan, through the Korean Peninsula, China, and northern Vietnam, with landlocked populations established in Japanese lakes such as Lake Biwa. Source

Did You Know?

  • Each fish defends a territory of roughly one square meter of algae-covered rock, fiercely attacking intruders—a behavior that forms the basis of Japan's traditional "tomo-zuri" decoy fishing method. Source
  • The breakdown of unsaturated fatty acids in its flesh gives off a distinctive melon-and-cucumber aroma, a trait that inspired its English name, sweetfish. Source

Where to See This Species

2 facilities · 0 individuals

山梨県立富士湧水の里水族館 (Yamanashi Kenritsu Fujiyuusuinosato Suizokukan)Yamanashi東富士五湖道路 山中湖ICから5分、中央高速 河口湖ICから20分。

山梨県立富士湧水の里水族館のWikipedia記事に飼育種として記載 Source

四国水族館 (Shikoku Suizokukan)Kagawa香川県綾歌郡宇多津町浜一番丁4（宇多津臨海公園内）。

四国水族館のWikipedia記事に飼育種として記載 Source

Conservation Story

Conservation Status

Plecoglossus altivelisはIUCNでLCです。地域の個体群では河川環境の変化に注意が必要です。

Habitat

東アジアの河川、河口、沿岸の汽水・海域。

Threats

  • 河川の分断
  • 水質悪化
  • 産卵場となる河床環境の変化

Conservation & Breeding Efforts

  • 魚道整備などによる回遊経路の確保
  • 産卵場・河川環境の保全

Sources

ja.wikipedia.org

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FAQ

Why is the ayu called a sweetfish?
Its English name comes from its distinctive, delicately sweet flavor and melon-and-cucumber aroma, produced as unsaturated fatty acids in its flesh break down. Source
How long does an ayu live?
Most ayu are annual fish that hatch, grow, spawn, and die within about a year, though landlocked populations in lakes such as Lake Biwa can live two to three years. Source

Source: ja.wikipedia.org en.wikipedia.org