The devilish pupfish: the most protected fish on Earth (3 photos)

Death Valley National Park, located primarily in the North American state of California and partly in Nevada, is considered one of the hottest and driest places on Earth. It can go for years without rain, and summer temperatures often exceed 50 degrees Celsius.





This "hellish" place contains a tiny cave lake with the rather symbolic name "Devil's Hole." It lies about 15 meters underground and is home to a unique, extremely rare species of fish found nowhere else.

The Devil's Puppyfish (Cyprinodon diabolis) is a 2-3.5 centimeter iridescent blue fish. The entire population of this species fits into a space the size of a small room—approximately 5 x 3.5 x 3 meters. There, at the entrance to the "Devil's Hole," is the main feeding and spawning area, where light and algae (the main source of its diet) are present. This is the smallest habitat of any vertebrate on Earth. Individual fish have been encountered deeper—down to 24 meters—but these are more likely rare excursions (out of curiosity?) than permanent residences. Remarkably, the "Devil's Hole" itself extends more than 152 meters deep, and its bottom has never been "found": the lake is a flooded tectonic fissure, narrowing as it descends and branching off into numerous channels.



Almost the entire natural habitat of the devil pupfish is shown in the frame. Equipment is used to monitor water levels.

Conditions here are lethal for most fish. The water temperature remains at 93-95 degrees Fahrenheit, as the "Devil's Hole" is connected to a deep groundwater system and is geothermally heated. Dissolved oxygen is low. Food is minimal: algae on rocks and microscopic organisms. But the devil pupfish has adapted to these difficulties and has lived here in isolation for tens of thousands of years.

Once, during the last Ice Age, the southwestern United States had much more water. The lakes were deeper, the rivers more voluminous, and the ancestors of the devil pupfish felt quite comfortable in these vast spaces. Then the climate changed, the waters receded, and one of the populations found itself trapped underground. It faced a choice: disappear from the face of the Earth or adapt to the hellish conditions. Evolution helped it choose the latter.

The devil pupfish lacks pelvic (belly) fins—they simply disappeared, becoming unnecessary in the cramped space. It is the only member of its species that does not exhibit territorial behavior—when you live with your family in a one-room apartment with nowhere to go, fighting over territory is pointless. Its metabolism has adapted to a minimum of food and oxygen. The average lifespan is only 6-14 months, but the fish begin reproducing within 2-3 months of birth.



In 2013, the Devil Puppy Minnow population numbered only 35 individuals. The species was on the brink of extinction. The US government allocated $4.5 million to create a special refuge with artificially recreated conditions, the "Devil's Hole." But the fish stubbornly refused to breed outside the walls of their native hell.

In the spring of 2024, the population grew to 191 individuals—a 25-year high. Their habitat is surrounded by a two-meter fence topped with barbed wire and motion sensors. This makes the Devil Puppy Minnow the most protected fish in the world.

This amazing creature reminds us: life is not about comfort, but about opportunity. When there's no choice, all that's left is to adapt.

And this forces us to take a different look at the search for extraterrestrial life. It's not necessary to look for "ideal" conditions similar to those on Earth. Sometimes a stable environment where stable chemical reactions and energy exchange are possible is enough. Then evolution takes over.