Researchers discover new species of acquifer-dwelling blind fish in Assam

Kochi: An international team of fish taxonomists from Germany, India and Switzerland scientifically described a new genus and species of blind, aquifer-dwelling fish from a dug-out well in a village in Assam. The discovery represents the first record of an aquifer-dwelling fish species from anywhere in Northeast India and the eastern Himalayan landscape, and it was published recently in Scientific Reports, a nature portfolio journal. Named Gitchak nakana after, ‘Gitchak', the Garo word for red which alludes to the striking red life colour of the fish, and ‘na-tok' and ‘kana', for a fish that is blind — referring to the absence of eyes — the species belongs to a new genus within the family Cobitidae. Gitchak nakana was only found in a single well and in very low numbers, and therefore the precise locality from where the species was collected was not disclosed. As the first groundwater-dwelling fish species described from Northeast India, the discovery of Gitchak provides clear evidence that this globally significant landscape harbours a highly specialised subterranean phreatobitic fauna of the kind that previously was only known from aquifers in the lateritic lowlands of Western Ghats in southern India. "Surprisingly, the cave mahseer from Meghalaya, Neolissochilus pnar, was recently available in the international aquarium pet trade, although a better understanding of its population size, wider distribution and potential threats to its habitat is still lacking. However, such information would be essential to plan conservation prioritisation and action for a subterranean fish with such a restricted distribution," said Rajeev Raghavan, assistant professor at Kerala University of Fisheries and Ocean Studies (Kufos), and the South Asia chair of IUCN SSC Freshwater Fish Specialist Group, who was part of the international team. The scientific team comprised Ralf Britz and Amanda Pinion (Senckenberg Museum, Dresden, Germany), Rajeev Raghavan (Kufos), Wimarithy Marak and Kangjam Velentina (Assam Don Bosco University, Guwahati), Yumnam Lokeshwor (Dhanamanjuri University, Manipur), and Lukas Rüber (Natural History Museum, Bern, Switzerland). "The subterranean fish research group led by Rajeev Raghavan was credited with some of the most interesting discoveries of groundwater-dwelling fishes of the Indian subcontinent, including Neolissochilus pnar, the world's largest cavefish. The group also described four subterranean fish species and one blind subterranean shrimp from various parts of Kerala. Subterranean fishes are one of the most enigmatic and evolutionarily distinct groups of fishes worldwide," said Kufos vice-chancellor A Biju Kumar.