CR

Lerma Chub

Algansea barbata

Declining

Overview

The Lerma chub is a species of freshwater fish in the family Leuciscidae, the shiners, daces and minnows. It is endemic to the uppermost Lerma River basin in the State of Mexico and Toluca Valley of central Mexico. This threatened species is up to about 13 cm (5.1 in) long.

Algansea barbata faces severe population decline primarily due to water extraction and diversion for agricultural and urban use, which has dramatically reduced water levels in its native river systems. Habitat degradation from pollution, sedimentation, and the introduction of non-native fish species has further compromised the remaining suitable environments. The species' restricted range in central Mexican river basins makes it particularly vulnerable to localized environmental changes and human activities.

Threat summary

Habitat

This freshwater fish inhabits clear, flowing rivers and streams in the central Mexican highlands, particularly in the Lerma River basin. It prefers well-oxygenated waters with rocky or sandy substrates and moderate current flow.

FRESHWATER· major

Conservation measures underway

Site/area protectionSpecies recoveryEx-situ conservation

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Opuntia pachyrrhiza

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Frequently asked questions

Why is Lerma Chub classified as Critically Endangered?
Lerma Chub is classified as Critically Endangered — facing an extremely high risk of extinction in the wild — because population sizes are very small, declining sharply, or restricted to a tiny range. Algansea barbata faces severe population decline primarily due to water extraction and diversion for agricultural and urban use, which has dramatically reduced water levels in its native river systems. Habitat degradation from pollution, sedimentation, and the introduction of non-native fish species has further compromised the remaining suitable environments. The species' restricted range in central Mexican river basins makes it particularly vulnerable to localized environmental changes and human activities.
Where does Lerma Chub live?
Lerma Chub occurs in Mexico. Country-level distribution data is sourced from the IUCN Red List and cross-referenced with GBIF occurrences.
What are the main threats to Lerma Chub?
The main threats to Lerma Chub are 2.1, 5.4, ai-1, and ai-2. The full IUCN-classified threat record for this species is detailed on the species page.

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