Caribbean coral reefs have been invaded by lionfish, showy predators with venomous spines. And they’ve found a new market to exploit: the ocean’s “twilight zone” — an area below traditional SCUBA diving depths, where little is known about the reefs or the species that inhabit them.

Researchers from the University of Washington and Smithsonian Institution have reported the first observed case of lionfish preying upon a fish species that had not yet been named. Their results, published May 25 in PLOS ONE, may indicate an uncertain future for other fish found in the largely unexplored deep-ocean coral reefs.

“Lionfish aren’t going anywhere, and we are faced with the fact that they are permanent residents on Caribbean reefs,” said lead author Luke Tornabene, curator of fishes at the Burke Museum of Natural History and Culture and an assistant professor at the UW School of Aquatic and Fishery Sciences. “The hope is that the learning curve is quick and other fish realize lionfish are predators. Right now, studies have shown some prey species to be pretty naïve.”