Chandragiri basin

Bhavania australis is a balitorid loach endemic to the Western Ghats mountains of southern India, recorded from Kerala, Tamil Nadu and Karnataka. An obligate dweller of shallow, fast-flowing, highly-oxygenated headwaters and minor tributaries, it has a flattened head and body and horizontally extended paired fins that form a powerful sucking cup for clinging to rocks. It is very rarely seen in the international aquarium trade but is maintained by a number of Indian aquarists.

The red-line torpedo barb, Dawkinsia denisonii, is a cyprinid endemic to Kerala and Karnataka in southern India. It is still often sold as Sahyadria denisonii. Extremely popular since it appeared in the trade in the late 1990s, it is listed as Endangered by the IUCN, and collection for the aquarium trade has been held largely responsible for its decline. Large numbers are produced in Southeast Asia and Eastern Europe. The similar D. chalakkudiensis is occasionally traded as this species and is more belligerent.

Opsarius bakeri is a fast-swimming cyprinid endemic to the Western Ghats of southwestern India, with records from many rivers in Kerala and Karnataka. It is traded as 'royal danio', 'blue-spotted hill trout' and 'blue-dotted mirror fish', and has a single row of bluish-green spots that get smaller with age. Its well-oxygenated, fast-flowing rivers are being polluted and degraded by exotic species and sand mining.

Opsarius malabaricus is a cyprinid from southwestern India, known with certainty only from the Payaswini and Valapattanam river systems in Kerala. Before its revalidation in 2015 it was usually traded as O. canarensis or O. bakeri 'orange fin'. Bluish-green spots along the body and broad orange margins on the dorsal and anal fins distinguish it. It probably inhabits well-oxygenated, fast-flowing rivers and streams.