June 28, 2005—It may not have taken much muscle to reel it in, but for scientists this fish is a big catch. Researchers recently discovered this new species of catfish in southern Mexico, and its traits are so distinct that it represents a whole new family of fish. The Philadelphia-based Academy of Natural Sciences, which took part in the research, announced the discovery on June 24.

Scientists made their find on the Lacantún River in the Mexican state of Chiapas, and they named the new species after its home waters: Lacantunia enigmatica. As its moniker suggests, this small fish is something of a puzzle. Not only is it the sole member of its scientific family so far, enigmatica is also the only known example of an ancient group of fish whose origins may trace back to the days of the dinosaurs.

The finding hinged on enigmatica's unique features, which differ from those of the common catfish.

Key variations are in the shape of the animal's skull, jaw muscles, air bladder—which fish use to rise and sink in water—and, perhaps most noticeably, the wispy barbels, or whiskers, around its mouth.

The discovery could bring renewed attention to the diverse biosphere of southern Mexico—especially the Lacantún, which the scientists say is facing increased environmental pressure from logging, farming, and the damming of rivers.

"The unexpected discovery of this enigmatic new family of fishes emphasizes how little we know about Mesoamerica's biotic legacy," the Academy's John Lundberg said. "This find reminds us that the most basic scientific inventory of Earth's biodiversity is woefully incomplete."

—Blake de Pastino

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