Devils Hole pupfish
A tiny blue fish that lives in one warm, deep desert pool at Death Valley and nowhere else on Earth, one of the rarest fish in the world.
Devils Hole pupfish at a glance
Cyprinodon diabolis DEV-ils-hohl PUP-fish; Cyprinodon diabolis is sip-RIN-oh-don dee-AB-oh-lis
- Type
- Fish · pupfish
- Diet
- Omnivore
- Size
- It is smaller than your thumb, only about 1 inch long. It lives in the smallest home of any fish, and any backboned animal, on the planet.
- Lifespan
- Very short, only about 10 to 14 months, roughly a year.
- Conservation
- Critically Endangered (IUCN); Endangered (U.S. Endangered Species Act)
Eats algae, tiny water animals, diatoms
It feeds mostly on the shallow, sunlit rock shelf just inside the pool, grazing on algae and tiny animals there. That one small shelf is where the fish finds nearly all its food and lays its eggs.
Should you worry?
The danger runs the other way: this is one of the rarest fish on Earth, and its whole world is one small pool that people are not allowed to enter. You can look down at Devils Hole from a fenced viewing platform, but no one may swim, touch the water, or reach in. Even small changes to that pool could wipe out the entire species, so watching quietly from the platform is the way to help.
The Devils Hole pupfish is a shimmering blue fish smaller than your thumb, about an inch long, and it lives in one place on Earth: a single warm, deep pool in a narrow cavern in the Nevada desert, inside a detached piece of Death Valley National Park. That pool is the smallest home of any fish, of any animal with a backbone, anywhere on the planet. The water stays near ninety-three degrees all year and holds very little oxygen, conditions that would kill most fish, and the pupfish spends its short life, only about a year, grazing algae and tiny animals off a shallow, sunlit rock shelf just inside the entrance.
Because that shelf is where the fish finds nearly all its food and lays nearly all its eggs, the whole species balances on a ledge the size of a room. Scientists count the entire population by hand, diver by diver. In the spring of 2024 they found 191 pupfish, the most in a spring count in twenty-five years. It is a hopeful number only when you learn that in 2013 the count fell to 35. That is how close this fish has come to being gone.
The famous thing about the pupfish is how much trouble people have gone to for something so small. In 1976 the highest court in the country ruled that pumping too much groundwater nearby was against the law, because it was lowering the water in Devils Hole and endangering this one fish. Today you can look down into the pool from a fenced platform, but no one may swim in it, touch it, or reach in. With a species whose entire world is one pool, watching quietly from the rail is the whole job.
Did you know?
- Every Devils Hole pupfish alive lives in a single water-filled cavern in the Nevada desert. Scientists count them by hand, and in spring 2024 they found 191, the most seen in a spring count in 25 years, up from an all-time low of 35 fish in 2013.
- The water in Devils Hole stays warm all year, about 93 degrees Fahrenheit, and holds very little oxygen, which would be deadly to most fish. The pupfish is built to survive there.
- In 1976 the highest court in the country ruled that pumping too much groundwater nearby was illegal because it was lowering the water in Devils Hole and threatening this one small fish.
Common questions
How many Devils Hole pupfish are left?
Very few. In spring 2024 scientists counted 191, the most in 25 years, and the population has been as low as 35. It is one of the rarest fish on Earth.
Where do they live?
In one warm, deep pool called Devils Hole, in the Nevada desert near Death Valley. They live nowhere else in the world.
Can I see them or touch the water?
You can look down at Devils Hole from a fenced viewing platform, but no one is allowed to enter or touch the water. The fish are far too fragile.
Why is the fish so easy to harm?
Its entire home is one tiny pool, so anything that changes that pool, like pumping too much groundwater nearby, could wipe out the whole species at once.