Breeding Topmouth Gudgeon

How Pseudorasbora parva breeds: a male-guarded nest under stones with eggs on the cavity ceiling, plus a critical warning on its invasive status in Europe.

Overview

The Topmouth Gudgeon (Pseudorasbora parva) is a hardy East Asian cyprinid that thrives in temperate fresh and brackish water at 5-22 degrees C. Reproduction involves male-built nests and male guarding of the eggs. Its high reproductive rate makes it a noted pest outside its native range.

Sexing

The species shows sexually dimorphic coloration in large adults, and individuals may take on different colours during the spawning season. Males clear and prepare nest cavities using specialised pearl (tubercle) organs.

Breeding Setup

Provide still or slow-flowing water with well-vegetated areas and hard surfaces such as stones, which the male uses as a nest site. The temperate temperature range of 5-22 degrees C suits an unheated, well-oxygenated tank. Sexual maturity is reached at around 3.0 cm in length.

Spawning Behavior & Trigger

The male constructs a nest under a stone, clearing the cavity, and the eggs adhere to the ceiling of the cavity. The female spawns repeatedly, three to four times per season. The male guards the eggs but leaves the nest before they hatch.

Egg & Fry Care

Eggs are guarded by the male during incubation and remain attached to the cavity ceiling until hatching. Because the male departs before hatching, the fry receive no further parental protection. Maximum reported lifespan is about five years.