Topmouth gudgeon

Amazing fact

Male topmouth gudgeon guard their eggs against other animals.

長野県水産試験場

Topmouth gudgeon in its habitat (illustration)

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An illustration based on the real animal.

A little discovery to share.

Male topmouth gudgeon guard their eggs against other animals.

Source長野県水産試験場 — モツゴ

THE REAL WORLD

The real Topmouth gudgeon

Scientific name: Pseudorasbora parva
Japanese name: モツゴ
Group: Freshwater animals

Order: Cypriniformes
Family: Cyprinidae
Genus: Pseudorasbora

Facts about the real animal.

Where the name “Topmouth gudgeon” comes from

They are also called kuchiboso, referring to their small mouths. They are also called ishimoroko because spawning males turn dark and grow white bumps around the mouth.

長野県水産試験場

It lives in Honshu west of the Kanto region, and in Shikoku and Kyushu.

鳥羽水族館 — モツゴ

It lives in many kinds of fresh water, such as lakes, marshes, lower rivers, irrigation canals, ponds and rice paddies.

鳥羽水族館 — モツゴ

It belongs to the carp family and is omnivorous.

鳥羽水族館 — モツゴ

How the Topmouth gudgeon lives

Their spawning season runs from spring into summer. Males carefully clean moss and mud off a stone. A male leads a female to the stone, where she lays her eggs.

三重県水産研究所長野県水産試験場

Basic data

Range: Honshu west of the Kanto region, Shikoku, and Kyushu

鳥羽水族館

Where the Topmouth gudgeon has been recorded

Records: GBIF.org (CC0 and CC BY 4.0 records, retrieved 2026-11-07). Map: Natural EarthSee the records on GBIF

Where it livesJapan Rivers and wetlands

Watch wild animals from a distance. Do not touch or feed them, and take care of the places where they live.

Names around the world

日本語: モツゴ
简体中文: 麦穗鱼
繁體中文: 羅漢魚
한국어: 참붕어
Español: Moroko de Piedra
Français: Goujon asiatique, pseudorasbora
Deutsch: Blaubandbärbling, Asiatischer Gründling
Português (Brasil): Góbio-de-boca-subida
Italiano: Pseudorasbora
Русский: Амурский чебачок

Names come from Wikidata and iNaturalist records. Where a language has no recorded name, we use the scientific name.

Sources and how we check

We check each fact against its source. The illustrations simplify how the real animal looks.

The classification (class, order, family, genus) follows Wikidata records, checked against GBIF. Classifications can change as research goes on.

The basic data are the values given in each source. They vary with how the animal is measured, whether it is male or female, and whether it lives in the wild or in captivity.

This page was translated from the original Japanese with the help of AI.

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