One of the world’s rarest fish discovered: a cave-dwelling ‘demon’

The planet’s biodiversity remains far from fully explored. Proof of that has emerged with the discovery of a bizarre new cave-dwelling fish species deep inside an underground cavern in the U.S. state of Alabama.

The find has stunned scientists because it was made in an area that had already been extensively studied in previous research. Its almost grotesque appearance and mysterious behavior have earned it the official name Demogorgonichthys arcanus, better known as the demon cavefish.

A creature straight out of science fiction

The new species was discovered in the waters of Bobcat Cave, a network of underground passages in northern Alabama located within a U.S. military installation. The area has long been recognized as home to unique species, but researchers believed its biodiversity had already been fully documented.

The discovery was made in February 2025 by Dr. Matthew Niemiller, a biological sciences expert from the University of Alabama in Huntsville, during a routine dive. There, he encountered a tiny fish species just a few centimeters long that had never previously been identified. The pale-colored specimen lacks eyes, has a pronounced humpback, an elongated snout, and sensory organs distributed across its skin.

Adding to its unusual appearance, its brain is visible through its nearly translucent skin due to its extremely low pigmentation. Researchers have also yet to identify its reproductive habits, and there are currently no obvious traits that distinguish males from females. Coincidentally, the discovery came around the release of the latest season of Netflix’s Stranger Things, leading Niemiller’s colleague, Dr. Jonathan Armbruster, to propose naming the species after the show’s iconic monster antagonist: the Demogorgon.

“What do you call a plain white, eyeless, rather nondescript thing? I mean, it’s hard to come up with descriptive names for something like that,” Armbruster, of the Auburn University Museum of Natural History, told CNN.

A species unlike any other

After an extensive investigation involving CT scans, genetic testing, and comparisons with other fish inhabiting the region, researchers concluded that the animal represents an entirely distinct species. The finding has surprised scientists, particularly because it had never been spotted during previous explorations of the cave system.

The discovery has also placed the demon cavefish among the world’s most critically endangered species. For now, researchers do not know how many individuals exist within the cave. Only 27 specimens have been observed to date, and given the cave’s limited size, scientists believe the total population is likely very small.

Its habitat, located within a restricted-access military zone, has helped shield the species from excessive pollution and large-scale urban development. However, the proximity of densely populated areas poses a significant threat, as contaminated surface water could eventually seep into the aquifer that sustains the cave ecosystem.

The discovery serves as another reminder of the extraordinary diversity of life on Earth and how much of it remains beyond our understanding.

Get closer to the game! Whether you like your soccer of the European variety or that on this side of the pond, our AS USA app has it all. Dive into live coverage, expert insights, breaking news, exclusive videos, and more. Plus, stay updated on NFL, NBA and all other big sports stories as well as the latest in current affairs and entertainment. Download now for all-access coverage, right at your fingertips – anytime, anywhere.

And there’s more: check out our TikTok and Instagram reels for bite-sized visual takes on all the biggest soccer news and insights.