Guwahati: In the quiet, rain-soaked slopes of the Siang Valley in Arunachal Pradesh, a slippery shadow wriggled through the mud one monsoon night in 2022. To the untrained eye, it may have seemed like just another swamp eel. But for a group of field biologists retracing the route of a century-old expedition, it was the glimmer of something much rarer—a fish believed lost to science for 110 years.
That elusive creature was Ophichthys hodgarti, a species first described in 1913 from specimens collected during the British Abor Expedition of 1911–1912. Known then as Moringua hodgarti, it was based on six specimens from the remote village of Rotung. And then, nothing. For over a century, no other record emerged. The species slipped into obscurity, becoming part of the long list of “lost” biodiversity in the Eastern Himalayas.
Until now.
“The rediscovery would not have been possible without the help of the local community,” said Nilanjan Mukherjee, the lead researcher of the rediscovery effort. “Especially the people who acted as our guides. It was due to their insights and help that we found the first one near Ramsing village, and then we knew we had found something extraordinary.”
Using dip nets at night and careful digging during the day, the team recovered several individuals from muddy irrigation channels and streamside leaf litter—just as the original expedition might have. Morphological and genetic analyses confirmed their hunch: O. hodgarti was back.
And it was full of surprises.
Unlike most of its swamp-dwelling cousins, O. hodgarti has paired gill openings—a unique feature among its genus. Its slender, scaley body is darkly mottled, helping it blend into the mud and evade predators—and scientists. Specimens burrowed furiously when disturbed, disappearing into the wet earth faster than a man could dig. In captivity, they would rise to the surface every few minutes to gulp air, surviving with a modified respiratory system that lets them thrive in oxygen-poor habitats.
“Studying them alive was very interesting,” Mukherjee said. “They were uncomfortable in deeper water and often were found on open wet ground, quite far from water.”
Local Adi communities know this fish well. They call it “Yuveh” and occasionally use it as food. But to science, it had become a ghost—until now.
The rediscovery also raises larger questions about what else lies hidden in the Eastern Himalayan mud. Arunachal Pradesh remains one of India’s least-explored biodiversity frontiers. Hydropower projects threaten to alter the very rivers and wetlands that harbor these fragile, ancient lineages. The team’s findings suggest that what’s lost may not be gone—but waiting, silent, in overlooked corners.
As the researchers pieced together the eel’s evolutionary story through DNA and bone structure, they found that O. hodgarti sits on a distinct branch of its evolutionary tree.
“In fragile landscapes like the Siang Valley, where large scale changes may take place through developmental projects, it is crucial that researchers expend more efforts to study and catalogue the species in that landscape” Mukherjee reflected. “Conservation can only be effected if we know what we stand to lose. It reminds us why exploration matters, and how much more there is to learn from indigenous communities.”
In the dim monsoon light of Arunachal’s forests, Ophichthys hodgarti swims once more—not just through streams, but back into science.
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