CR

Melanotaenia ajamaruensis

Declining

Overview

The Ajamaru Lakes rainbowfish is a species of rainbowfish in the Melanotaeniinae subfamily. It is endemic to the Ayamaru Lakes in West Papua, Indonesia. The fish was announced in 1996 based on its IUCN status, then rediscovered in 2007 in the Kaliwensi river, Sorong, West Papua.

Melanotaenia ajamaruensis faces severe risk due to its extremely restricted range within the Ajamaru Lakes, where introduced predatory and competitor fish species have disrupted native fish communities. Water quality decline from agricultural runoff and sediment input further degrades the lake habitat this species depends on entirely. The combination of a single-locality distribution and ongoing ecological disturbance makes the species highly susceptible to rapid, irreversible population decline.

Threat summary

Habitat

This species inhabits clear, fast-flowing freshwater streams and tributaries within lowland tropical rainforest watersheds of West Papua's Bird's Head Peninsula. It prefers areas with rocky substrates, abundant aquatic vegetation, and well-oxygenated water typical of pristine mountain-fed river systems.

Wetlands (inland) - Permanent freshwater lakes· major

Conservation measures underway

Species recovery

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Chilatherina pricei

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Mamah Rainbowfish

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EN

Speckle-faced Bent-toed Gecko

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Acropora hemprichiiEN

Acropora hemprichii

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VU

Bacan Myzomela

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Hopea coriacea

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Frequently asked questions

Why is Melanotaenia ajamaruensis classified as Critically Endangered?
Melanotaenia ajamaruensis 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. Melanotaenia ajamaruensis faces severe risk due to its extremely restricted range within the Ajamaru Lakes, where introduced predatory and competitor fish species have disrupted native fish communities. Water quality decline from agricultural runoff and sediment input further degrades the lake habitat this species depends on entirely. The combination of a single-locality distribution and ongoing ecological disturbance makes the species highly susceptible to rapid, irreversible population decline.
Where does Melanotaenia ajamaruensis live?
Melanotaenia ajamaruensis occurs in Indonesia. Country-level distribution data is sourced from the IUCN Red List and cross-referenced with GBIF occurrences.
What are the main threats to Melanotaenia ajamaruensis?
The main threats to Melanotaenia ajamaruensis are 8.1. The full IUCN-classified threat record for this species is detailed on the species page.

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