Bony fish · Cypriniformes · Leuciscidae

Iberian Straight-Mouth Nase

Pseudochondrostoma polylepis

Near Threatened

It could become endangered in the near future if current threats go unchecked. See full glossary

A cyprinid endemic to the Iberian Peninsula, native to the Tagus, the Douro and other rivers of the western half of the peninsula. It has a ventral mouth with a straight horny lip with which it scrapes the algae clinging to the stones of the riverbed. It forms large shoals in the middle reaches of rivers.

Size

20 cm – 50 cm

Diet

Herbivore

Feeds mainly on plants.

Social structure

Colony

Lives in large concentrations, often for breeding reasons.

Sighting difficulty

Moderate

FreshwaterHerbivore Colonial Near Threatened Fish Freshwater

2countries 21parks2same family

Fun facts

GeneralEndemic to Iberia; it scrapes algae off the stones with its mouth.
Its lower lip is a sharp horny plate, almost a blade, adapted to scraping the algal biofilm from river cobbles.
It makes migrations of tens of kilometres upstream to spawn over gravel, movements that are blocked by dams and weirs.
It is an Iberian endemic: it lives only in the basins of the Tagus, the Douro, the Guadiana and a few smaller rivers of Portugal and Spain.
It scrapes the algal biofilm off stones with a mouth whose lower lip is horny and sharp-edged, an adaptation it shares with the other Iberian nases.
Its populations suffer from dams, which fragment the rivers and stop it running upstream to its spawning grounds, and from introduced species such as the wels catfish and the black bass.
The Iberian freshwater fish fauna has an extremely high share of endemics, and this genus is a good example: each major basin has its own species of nase.