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Rarest Fish on Earth Endures Death Valley's Harshness
13 Jan
Summary
- Devils Hole pupfish inhabit a single Nevada cave with extreme heat and low oxygen.
- Population fluctuates dramatically, with recent highs and subsequent plunges after earthquakes.
- Biologists intervene with captive-bred fish and food to aid survival during recovery.
Deep within Death Valley, Nevada, lies Devils Hole, the sole refuge for the Devils Hole pupfish, considered the rarest fish on Earth. This tiny species, measuring only an inch long, endures extreme conditions including constant 33°C water and critically low oxygen levels. Their habitat, the top 15-24 meters of a cavern plunging 150 meters deep, is the smallest vertebrate habitat globally.
Recent seismic activity significantly impacted the pupfish population, causing numbers to plummet from 191 in spring 2024 to just 38 in 2025 after disrupting their primary food source, algae. In response, biologists swiftly implemented a preparedness plan, releasing captive-bred individuals and providing additional sustenance to support the dwindling numbers until the algae can recover.
These pupfish, isolated for potentially thousands of years, showcase remarkable adaptability, even lacking pelvic fins. Despite threats from predators like diving beetles and environmental challenges like flash floods, conservation efforts at the Ash Meadows National Wildlife Refuge aim to safeguard this unique species.
