Manipur: New hill-stream catfish Exostoma nasibarbatum found in Chandel

A previously unknown species of small hill-stream catfish has been described from Manipur's Chandel district, adding to the list of fish found only in the remote rivers that drain towards Myanmar, The Assam Tribune reported on Sunday.

The fish, named Exostoma nasibarbatum, belongs to the glyptosternine group of catfishes, which are adapted to life in fast, rocky mountain streams. The description was published in the Journal of Natural History.

Where it was found

The species was found during a fish survey of the Bupal stream, a tributary of the Dujang river in the Chindwin river system along the India-Myanmar border. The research team was led by Dr Bungdown Shangningam, assistant professor in the Department of Zoology at Dhanamanjuri University in Imphal, with PhD scholar Paya Torisha Anal.

After studying the body shape and features of the specimens in detail, the researchers concluded that they did not match any known Exostoma species. According to the report, Dr Shangningam said these small catfishes are rarely found and live in remote parts of the Dujang river, and that this is the second fish species to be described from the Chakpi area of Chandel district.

Built for fast water

The new catfish lives in turbulent water over boulders and rocks. Like its relatives, it has a strongly flattened head and body, large paired fins with adhesive ridges and flattened whiskers (barbels) that help it cling to stones instead of being swept away.

Its name refers to its most distinctive feature: a long nasal barbel near the nostril that reaches past the back edge of the eye. "Nasibarbatum" combines the Latin words for nose (nasus) and beard (barba).

Why it matters

According to the study, 23 valid species are recognised in the genus Exostoma across South and Southeast Asia, seven of them in the Chindwin-Irrawaddy drainage. The researchers said the find in Manipur's largely inaccessible upper Chindwin streams suggests ongoing speciation over evolutionary time, and that more surveys are needed in areas that remain poorly explored and may still hide undescribed aquatic species.

Dr Shangningam, who has earlier worked with the Union Ministry of Environment, Forest and Climate Change and as a postdoctoral fellow at the Zoological Survey of India, has described 39 new fish species from India and Myanmar since 2012, most of them catfishes, the report said.

Manipur's hill streams are part of the Indo-Burma biodiversity hotspot, and researchers from the state's universities have described several new fish species from the Chindwin and Barak river systems in recent years.