noun
stone moroko; topmouth gudgeon
A small freshwater fish (Pseudorasbora parva) native to East Asia, often found in ponds and slow-moving streams.
近所の池でモツゴがたくさん泳いでいる。
Many stone moroko are swimming in the neighborhood pond.
The origin of the name is uncertain. The kanji 持子 is ateji and does not reflect the etymology.