Schistura Densiclav: New species of cave-dwelling fish found in Meghalaya

Hindustan Times

25-05-2025

A new species of cave-dwelling fish was discovered in Meghalaya's Mawsynram town by a team of researchers from Gauhati University, Lady Keane College in Shillong, and the ICAR-National Bureau of Fish Genetic Resources in Lucknow.
The discovery was made in Krem Mawjingbuiñ, a cave located just 15km from Mawsynram beside Sohra (Cherapunji). Despite the cave's remote location and inaccessibility, the team of researchers undertook a challenging expedition that led to the unearthing of this unique species of stone loach.
'This discovery highlights the untapped biodiversity thriving in Meghalaya's underground ecosystems,' said Professor Dandadhar Sarma, Head of the Zoology Department at Gauhati University.
'It's the ninth new fish species we've described from Northeast India, and the sixth known cave-associated fish from Meghalaya.'
What makes Schistura Densiclava particularly intriguing is its deviation from the expected evolutionary adaptations of hypogean (underground-dwelling) species. Most cave fish lose their eyesight and pigmentation over generations, relying on heightened non-visual senses to navigate pitch-dark waters. But S. Densiclava still sees — and shows off its colours too.
With a pale yellow-green body and bold black bars numbering between 14 and 20, the fish sports a distinctive thick stripe near its dorsal fin — the very feature that earned it the species name densiclava, meaning 'dense stripe' in Latin.
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Published in the Journal of Fish Biology, a prestigious journal by the Fisheries Society of the British Isles, the discovery has earned plaudits from across the world.
Assam's education minister Ranoj Pegu took to social media platform X (formerly Twitter) to congratulate the team, calling it 'a proud moment for Northeast India's scientific community.'
Unlike fully cave-adapted species such as Schistura papulifera and the ghostly Neolissochilus pnar — which are pigmentless, blind, and highly specialised troglobites — S. Densiclava represents a different evolutionary strategy. It is a troglophile, a species that thrives inside caves but isn't entirely dependent on subterranean life. It retains its vision and pigment, suggesting that it still teeters between two worlds — the surface and the subterranean.
Yet field reports suggest S. Densiclava may be shifting further into darkness. It was found exclusively in a cool, fast-flowing stream some 60 metres inside the cave, where water temperatures hover at a chilly 18°C and oxygen levels are low. The fish's resilience in such nutrient-scarce conditions is remarkable. Its diet includes copepods, tiny shrimp, insect fragments, and even bat guano — a feast made possible by the web of interdependence between cave organisms.
According to Kangkan Sarma, one of the study's lead authors, the species shows clear sexual dimorphism.
'Males are slimmer with irregular patterns and puffier cheeks, while females are more robust and display more uniform markings,' he noted, adding, 'DNA sequencing confirms that this is a genetically distinct species, unlike any other Schistura found in the region'.
The East Khasi Hills region, where Krem Mawjingbuiñ lies, is a part of Meghalaya's celebrated cave systems — one of the richest and least explored subterranean landscapes in the world. With over 1,700 caves and cave locations documented, but only a fraction thoroughly studied, Meghalaya is considered a global hotspot for cave biodiversity. The state's unique karst topography, formed by the slow dissolution of soluble rocks like limestone and dolomite, provides ideal habitats for specialised and often endemic species.
The discovery of S. Densiclava adds to a growing list of fascinating finds from Meghalaya's caves.
In 1998, Schistura papulifera, another loach from the Siju Cave in South Garo Hills, was the first troglobitic fish to be described from India. More recently, in 2019, researchers stunned the scientific world with the announcement of Neolissochilus pnar, a large blind fish discovered in the Um Ladaw Cave system. With no eyes and no pigmentation, N. Pnar was likened to the 'golden mahseer of the dark.'
One of the most striking aspects of the Schistura Densiclava find is the pristine condition of its habitat.
'There were no visible signs of human disturbance inside Krem Mawjingbuiñ,' said one researcher, noting how seasonal access and the surrounding dense forest have kept the cave largely untouched by tourism or development.