Bagarius bagarius

Bagarius: from 'Vaghari', a local name in Calcutta (Kolkata).

bagarius: as above.

Currently considered to have a wide but disjointed distribution extending southeastward from the Indus River, Pakistan, and including the Ganges and Brahmaputra in India, Nepal, and Bangladesh, the Irrawaddy and Salween in Myanmar, the Mekong system in Laos and Cambodia, Chao Phraya in Thailand, and several rivers of the Malay Peninsula.

This distribution appears doubtful, however, and it seems likely that future studies will reveal that Indian and Southeast Asian populations are not conspecific with several species possibly involved (see 'Notes').

Type locality is 'Ganges River, India'.

Mostly collected from larger river channels and typically associated with fast-flowing, turbulent rapids where it takes shelter among boulders and large rocks.

Suitable only for public installations or the very largest, highly-specialised private aquaria.

Prefers dim lighting and access to refuges in the form of driftwood, large rocks or lengths of plastic piping.

A large, mature filter system, rigorous maintenance regime comprising weekly water changes of 50-70% tank volume, and provision of highly-oxygenated water with plenty of movement should be considered mandatory.

An obligate predator feeding on smaller fishes, amphibians, crustaceans and other invertebrates in nature but in most cases adapting well to dead alternatives in captivity.

Young fish can be offered chironomid larvae (bloodworm), small earthworms, chopped prawn and suchlike while adults will accept strips of fish flesh, whole prawns/shrimp, mussels, live river shrimp, larger earthworms, etc.

This species should not be fed mammalian or avian meat such as beef heart or chicken since some of the lipids contained in these cannot be properly metabolised by the fish and may cause excess fat deposits and even organ degeneration.

Similarly there is no benefit in the use of 'feeder' fish such as livebearers or small goldfish which carry with them the risk of parasite or disease introduction and at any rate tend not have a high nutritional value unless properly conditioned beforehand.

Best maintained alone.

Unrecorded.

There is considerable confusion surrounding the identity of B. bagarius with its name having been widely applied to a relatively small species that is said to reach only 200 mm8 in SL and considered to be common in northern India and much of Indochina.

However, the genus is in urgent need of review with a number of additional taxa thought to exist, and B. bagarius possibly representing the only species found in the Indian subcontinent and therefore not conspecific with fish from Indochina. If this is the case, it is capable of reaching 2 metres in length.

Following Roberts (1983) B. bagarius and B. yarrelli can be distinguished from other congeners by the following characters: cranium and predorsal plate covered with horny skin differentiated into elongate unculiferous plaques; supraoccipital crest and predorsal plate without sharp ridges; skin on sides of head and on body with elongate unculiferous plaques similar in shape but generally smaller than those on dorsal surface of head; body depth 4.7-8.5 (mean 6.0); no large darkly pigmented spot or blotch on side of body between darkly pigmented areas near dorsal and adipose fins.

B. bagarius can be told apart from B. yarrelli as follows: pelvic-fin origin usually anterior (vs. posterior in B. yarrelli) to a vertical line through base of last dorsal-fin ray; adipose-fin origin slightly to markedly posterior (vs. anterior to, on, or slightly posterior) to a vertical line through anal-fin origin; total external gill rakers on first gill arch 6-9 (vs. 8-11); pectoral-fin rays 9-12 (vs. 11-14); elongate neural spines 4-8, distally expanded (vs. 2-5, slender ); abdominal vertebrae 17-20 (vs. 21-24).

The genus Bagarius is distinguished from all other genera in the putative subfamily Sisoridae by having markedly heterodont teeth in the lower jaw. Teeth are present in two or three outer rows of relatively numerous, close-set conical teeth, and one or two inner rows of less numerous, widely separated, and much larger conical teeth (vs. dentition of the lower jaw consisting of only small conical teeth, or a roughened bony plate).