Cauvery basin

Barilius 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.

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.

Dawkinsia rubrotinctus is a cyprinid from southern India, considered widespread throughout the Cauvery drainage in Karnataka, Kerala and Tamil Nadu. It may have appeared in the trade under the misapplied names Puntius arulius and P. tambraparniei. Three small, well-defined dark body markings separate it from D. arulius, D. srilankensis and D. tambraparniei, in which the markings are larger and more diffuse.

The peninsular 'danio', Devario neilgherriensis, appears endemic to tributaries of the Bhavani river system in the Nilgiri Hills, southern India. It is almost unheard of in the trade and little is known about it. Day described it with silvery flanks and a broad, indistinct steel-blue stripe bounded above and below by a narrow bright yellow band. Several of its hill-stream habitats lie around 2000 m AMSL.

Mesonoemacheilus petrubanarescui is a loach from the Netravati and Kabini river basins in the Western Ghats of southern India. It may be endemic to these two drainages. The dorsal surface carries 7-8 dark, saddle-shaped markings and the flanks a varying number of broken bars. It is unclear if it has been traded outside India, but it may turn up among shipments of M. guentheri or M. triangularis.

Paracanthocobitis mooreh is a nemacheilid loach known only from the Godavari, Krishna and Kaveri (Cauvery) systems in western and southern India. An incomplete lateral line ending near the pelvic-fin origin, with small, mostly vertical blotches along it connected to the dorsal saddles, separates it from congeners. It favours stretches of streams and small rivers where leaf litter collects over sand, cobbles and boulders, and is generally non-aggressive.

Pethia nigripinnis is a small cyprinid of cool, flowing hill streams in Kerala and Tamil Nadu, apparently endemic to the southern Western Ghats. Adult males have black dorsal, anal, pelvic and pectoral fins. Its need for cooler temperatures makes it unlikely to suit the general community aquarium, and it will probably do best alone or with comparably-sized species needing similar conditions.

The two-spotted barb, Puntius bimaculatus, is a small cyprinid from Sri Lanka and southern India. It lives in flowing hill streams and quieter stretches in the middle reaches of rivers, but tends to be absent from lowland environments. Also called the 'redside barb', it has 7 branched dorsal-fin rays and round dark spots at the base of the dorsal and caudal fins. Generally very peaceful, it is a schooling species and at least 6-10 should be kept.

The red-line torpedo barb, Sahyadria denisonii, is a cyprinid endemic to Kerala and Karnataka in southern India. 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 S. chalakkudiensis is occasionally traded as this species and is more belligerent.

Schistura denisonii is a nemacheilid loach from the Western Ghats of southern India, described from the Bhavani River in the Cauvery system. Widely referred to Nemacheilus, it matches the diagnostic characters of Schistura. The number and arrangement of its vertical body bars vary greatly, and whether it represents a complex of species or a single taxon remains unclear. Feisty, it is largely unsuitable for the general community aquarium.

The goonch, Bagarius yarrelli, is a very large sisorid catfish recorded from the Indus in Pakistan east through Indochina to Sumatra and Borneo. Also known as the 'giant devil catfish' and 'sand shark', it reaches 1300 to 2000 mm and is fished for food across much of its range. That wide distribution appears doubtful, and Indian and Southeast Asian populations may prove not to be conspecific. It lives among boulders in the fast, turbulent rapids of large rivers.

The porthole bagrid, Hemibagrus punctatus, is a catfish known only from the Cauvery (Kaveri) river system in southern India. The IUCN lists it as Critically Endangered (possibly extinct), and at its confirmed localities in the Kabini, Bhadra and Moyar systems it was last collected in 1998 or earlier. It has been available only very occasionally in the aquarium trade, and its flanks carry dark spots arranged in vertical columns.

Gymnostomus ariza is a cyprinid widely distributed from the Indus basin in Pakistan through India, Bangladesh and Myanmar. Growing to around 300 mm SL, it inhabits flowing streams and tributaries with clear water. It has a confusing taxonomic history, having been placed in Bangana, Cirrhinus and Labeo in recent years. It breeds in temporarily-inundated zones in the wet season and is also produced commercially for food.