Sahyadria denisonii (Denison barb, red-line torpedo barb, or roseline shark) is a species of cyprinid fish endemic to the fast-flowing hill streams and rivers of the Western Ghats in India. It is commonly seen in the aquarium trade.
Denison barb is endemic to the Achenkovil and Chaliyar rivers. Specifically, they are found in four locations — Cheenkannipuzha (a major tributary of Velapattanam River), the Achankovil river, the Chaliyar river and near Mundakayam town. The species has an estimated range of 8,805 km2 (3,400 sq mi). S. denisonii is a benthopelagic species that is gregarious and shoals are known to occur in rocky pools with thick vegetation along their banks. They thrive in a subtropical climate in water with a 6.8–7.8 pH, a water hardness of 5–25 dGH and a temperature range of 65 to 79 °F (18 to 26 °C).
As reported by Practical Fishkeeping in January 2009, new research by team of scientists from India suggests that the species is being over-exploited for the aquarium trade, potentially placing it at risk of extinction. In spite of being listed as Endangered by local assessment reports the fish had been promoted as an ‘Export item’ by several government agencies. The population structure, age, growth, mortality and harvest intensity in the Valapattanam River was studied and suggests that the species is being over-exploited.