A Fishy Cerberus
Deep in the Amargosa Desert there is a pit to which we have found no bottom. This is Devils Hole, a geothermal pool that stays at a constant 91°F and it is over 500ft deep. You are not welcome here! Turn back, the entrance is guarded by the most tenacious of beasts!
Alright, my mighty Cerberus is a fish that gets at most 1.2 inches. But I did not lie! Exploration of Devils Hole and your ability to go there are indeed halted by this fish. This gem is the rarest fish in the world. At the time of writing this, (May 7th, 2026) we just got an up to date pupfish count and they found 77! (Source) Last year at the same time, they only found 38. Unlike more elusive fish we might have trouble finding, every last (wild) Devils Hole Pupfish can be found here in Devils Hole.
Devils Hole is only 72ft long and 11.5ft wide. If you look in the picture above, you'll see a green patch. This is an 11ft by 16ft rock ledge that gives our gluttonous Cerberus all its food. They eat everything that grows here like scuds, algae, diatoms, snails, flatworms, and it would seem that they eat quite a bit of limestone on accident. It's a very small and fragile habitat that gets its nutrients from dust and bird poop, all the while nutrients slowly fall into the bottomless pit.
Sometimes nutrients very quickly fall down the pit. Devils hole is a small outlet for a large amount of water, so earthquakes really effect it even if they're far away. It's honestly really hard to watch thinking about our little fish, but events like earthquakes and flash floods kill fish and wash their food supply away down the pit. But I did not lie! The Devils Hole Pupfish is tenacious! When they detect seismic activity they flee deep into the pit to have an emergency breeding event! It's quick thinking like that which keeps a small population like this alive!
As strange as it maybe, they actually require a low population in order to survive. Maybe not as low as 77 or even 38, but they had about 500 individuals when we started counting. If they were to eat up all their food, there'd be a mass dying just the same. As a result, they only live a little over a year and their eggs have a low sucess rate. This is pretty good when population is high but that's not really where we are now.
While there have been protections for in situ, or in place, conservation since the 60s. There have been a number of ex situ, out of place, projects as well. All of them have failed except most recently they made a replica of the stone ledge and keep it temperature controlled. When they saw the numbers as low as 38 last year, they made an emergency decision to release 19 captive raised pupfish into the hole! Who knows if that was a good idea, I certainly don't know. The simulated environment didn't have the hole or seismic activity so they might not be as prepared for that.
It would seem our fish has caused some controversy! It became one of the first animals to be protected under the Endangered Species Act in 1967 at the same time as a large farm tried to open up nextdoor. They drilled several wells and the water level in Devils Hole began to drop. This became a whole thing, the Supreme Court got involved. People cried out for the imperiled fish just as people cried out for the poor millionaires. A local journalist threatened to dump pesticide in the hole. The Desert Fishes Council released "Save the Pupfish" bumper stickers and the county commissioner released "KILL THE PUPFISH" stickers in turn. I can't really imagine a world where we let a millionaire kill a species for no reason but yeah people got real mad on their behalf then I guess. I'm providing YOU with some stickers so you can pick a side!
I think this fish is so pretty, so resilient, and just the concept of it's only role in life is to live at the top of the bottomless pit is so cool. We don't know too much about them because even observing them could be disruptive. Before a dive, all equipment has to be sanitized and quarantined for 30 days. There's so few of them and they could've been in this hole for 200-60,000 years. We just can't know. It's so cool to find something so finite that we just can't completely understand. They live in such an extreme situation that I can't even fault them for being imperiled.