Some hills in northern Alabama are burial mounds from the Copena people who lived there 2,000 years ago. Some contain decommissioned nerve gas from the cold war. But one holds a portal to the underworld—a low-slung knoll in a restricted military installation leads to a cramped but sprawling limestone network called Bobcat Cave, where scientists have discovered a strange, eyeless creature they’ve dubbed the demon cave fish.
The cave isn’t exactly welcoming to human visitors. “You’re stooped to hands and knees, crawling, and depending on the water level, you could be in neck-deep,” says Matthew L. Niemiller, a cave biologist at the University of Alabama in Huntsville. But because the system is a stronghold for the endangered Alabama cave shrimp, monitoring teams have explored the cave nearly every month since the early 1990s.
Amanda Montañez; Source: Centers for Disease Control and Prevention
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Despite this scrutiny, the demon cave fish was discovered only recently and completely by chance. On a routine survey in February 2025, Niemiller slipped in the red Alabama mud and fell headlong into a deep pool of water—and found himself face-to-face with a creature he didn’t recognize. This fish had a humped back and a slightly duckbilled snout, and, unlike the slightly more colorful Southern cave fish already known to inhabit the system, it was so ghostly white it looked blue under their headlamps. “It’s a shock and kind of embarrassing, in a way,” that it escaped notice for so long, says Niemiller, lead author of a paper presenting the new species and genus in Scientific Reports.
Genetic analyses suggest the demon cave fish and the Southern cave fish aren’t closely related and made their way underground separately: it appears they lost their vision because of different mutations. The study authors say it’s surprising to see two cave fish species living in not just the same cave system but the same pools and chambers. Whereas other cohabitating cave fish are like neighbors, the demon and Southern cave fish are like roommates—if those roommates had been trapped together for millions of years and potentially snacked on each other’s children.
Niemiller and his team have named the new species Demogorgonichthys arcanus, a wink to the otherworldly creature that emerged in a secret federal lab in the Netflix series Stranger Things. The finding is a humbling reminder of how much biodiversity remains undocumented even in the best-explored caves, says Suzanne McGaugh, an ecologist and cave fish expert at the University of Minnesota, who wasn’t involved in the new study. “We owe a debt of gratitude to them for their discovery,” she says.
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