March 11, 2009--While he may not vant to suck your blood, the male fish seen above does sport spooky-looking fangs that have earned it the name Danionella dracula.
Researchers at London's Natural History Museum found several of the new species (bottom) in a tank of aquarium fish. Initially museum staff had thought the 0.7-inch-long (1.7-centimeter-long) creatures, caught in Myanmar (Burma), were part of an already known, related species.
"After a year or so in captivity, they started dying," museum scientist Ralf Britz told BBC News.
"When I preserved them and looked at them under the microscope, I thought, my God, what is this, they can't be teeth."
In fact, the fangs are not true teeth—the line of fish that gave rise to D. dracula is thought to have lost teeth around 50 million years ago.
By staining the bone and dissolving away tissue to reveal the full jawbones of dead specimens (top), Briz found that the odd species has rows of bony jaw protrusions (inset) that lack the pulp cavities and enamel caps of true teeth.
Despite their ghoulish appearance, the fangs likely aren't used for feeding.
"We did not study stomach contents, but we know that its close relatives live on small crustaceans
and other small invertebrates," Britz said in an email to National Geographic News. "In captivity it readily accepts brine shrimp [larvae], tiny nematodes, and even very fine flake food."
Based on the behavior of live "Dracula" fish, the researchers think the males use their extralong fangs to spar with each other during aggressive displays. The findings are described this week in the online edition of the Proceedings of the Royal Society B.