The Denison’s Barb (Sahyadria denisonii) is another example of how little people in India know when it comes to the diversity of their river-dwelling fish. This is again, a member of the carp family, Cyprinidae, of the genus Sahyadria. As of now, there are only two species, Sahyadria denisonii and Sahyadria chalakkudiensis. Both are endemic to the Western Ghats of South India (in the states of Karnataka and Kerala). The former is extremely popular in the aquarium trade, both in India and abroad. In fact, such is the demand in the international market that their population has plummeted, raising fears of the species’ eventual extinction. This is a case that resembles that of the Clown Loach of Indonesia, which like the Denison’s Barb, cannot be raised in captivity.

The genus Sahyadria is restricted to the streams and rivers of the Western Ghats, a chain of forested and rain-drenched mountains rising sharply above the western coast of peninsular India. The Barb lives in rocky pools with overhanging vegetation. A gregarious species, it spawns during the months of November-January, when the states of Karnataka and Kerala are hit by the North East Monsoon. In fact, Sahyadria is derived from ‘Sahyadri’, the name used for these mountains in India. The species was described by the British army surgeon and naturalist Francis Day (in 1865) who named it in honour of Sir William Thomas Denison (Governor of Madras from 1861 to 1866).

Day was a pioneering ichthyologist and played a crucial role in cataloging the aquatic fauna of South Asia through his two-volume work, ‘The Fishes of India’. He called it Labeo denisonii. The species was caught and examined in the town of Mundakayam, in Kerala’s Kottayam District. It is a striking fish, with a torpedo-shaped body, silvery scales, and two lines, one red (above) and one black (below), running from the snout, across the eyes and along the sides. The dorsal fin has a streak of red while the tail fins have patches of yellow and black. No wonder that it is such a catch for aquarium hobbyists and famous as the Red Line Torpedo Barb, Rose Line Shark and Miss Kerala. An even more evocative name is ‘Chorai Kanni’ (Bleeding Eyes) in Malayalam, the native language.

The last name is quite appropriate, given the fact that the great majority of live fishes exported from India as part of the international aquarium trade are members of this species (as much as 60%). But the fish has paid a heavy price. Its occurrence in only a handful of rivers and streams (Chandragiri, Valapatnam, Karyangod, Chaliyar, Achenkovil, Kuttiyadi, Bharatapuzha, Sullya, Kuppam, Iritti, Anjarakandipuzha and Bhavani), unsustainable harvesting, and the destruction and pollution of the Western Ghats’ pristine wilderness has made it an endangered species. These fishes are not known to breed in the wild.

The Government of Kerala has stepped in to conserve the species, by placing restrictions on the capture and sale of Denison’s Barbs. However, it might be efforts to raise the fish in captivity that will save it from extinction. Breeding of the species has been successfully replicated in Chester Zoo (Cheshire, England), College of Fisheries (Ernakulam, Kerala), and by hobbyists from Chennai (Tamil Nadu). There are reports of the species being captive bred for export in Singapore and Indonesia. If the captive breeding experiments are replicated on a commercial scale, they will ease the pressure on the wild population, something that is crucial given the fact that this is an endemic species of rare beauty.

Image Attribution: The image above is sourced from Wikimedia Commons and shows a Denison’s Barb. The image was uploaded by Ananda Rajakumar.

Reference: