In a major breakthrough for freshwater taxonomy, a team of researchers from Dhanamanjuri University's Department of Zoology has discovered a rare, highly specialized species of freshwater catfish. The micro-endemic species, scientifically named Exostoma nasibarbatum, was identified in the remote Bupal stream of the Chandel district, a high-energy aquatic system belonging to the Chindwin River basin along the Indo-Myanmar border.
The landmark findings were published online in the internationally recognized Journal of Natural History, published by Taylor & Francis.
The exploration team was led by Assistant Professor Dr. Bungdon Shangningam and PhD scholar Paya Torisha Anal, whose extensive fieldwork culminated in the collection of the physical specimens from the stream.
Unlike typical open-water fish, members of the glyptosternine genus Exostoma, which belongs to the Sisoridae family, are physically engineered to withstand rushing mountain waters. In these high-velocity habitats, staying anchored to the riverbed is a critical matter of survival.
To thrive close to the riverbed, Exostoma nasibarbatum features a strongly flattened head and compressed body that allow it to hug rocky surfaces, drastically minimizing the drag force of sweeping currents.
Crucially, its enlarged paired fins are lined with adhesive striae—microscopic friction ridges that function like natural suction pads to grip slick boulders. Furthermore, its lips feature unique patterns of anastomosing, rounded striae that distinguish it from its 23 global genus congeners.
The specific name nasibarbatum stems from a combination of the Latin words nasus, meaning nose, and barba, meaning beard. This points directly to the creature’s most defining trait: an unusually long, whisker-like nasal barbel that extends prominently past the rear edge of its eye socket. Since these fast-moving mountain streams are frequently turbulent, the elongated tactile barbel serves as a critical sensory organ, allowing the catfish to locate food by touch and chemical signatures rather than relying on sight.
The specimens were retrieved from cold, pristine freshwater running between 12°C and 14°C, underlining the species' reliance on undisturbed environments. The researchers emphasized that the surrounding riparian forest ecosystems are essential for preserving the optimal water quality and temperature required by these current-loving, rheophilic fish.
Since they are highly sensitive to water pollution, siltation, and canopy degradation, the discovery serves as a vital reminder of the fragile ecology within the Indo-Burma biodiversity hotspot, highlighting the critical need to preserve remote catchments from human interference and destructive fishing techniques.