Bagrichthys majusculus

Described from the Mun River, Ubon Ratchathani Province, eastern Thailand, a tributary of the Mekong River, and is known only from the Mekong and Chao Phraya systems. It has been recorded from Mekong tributaries in Laos and presumably occurs in Cambodia as well.

Typically inhabits large, turbid rivers with muddy substrates and slow flow and moves moves into flooded riparian zones to spawn during the wet season.

A tank with base measurements of 120 ∗ 45 cm48 ∗ 18 in should be the smallest considered.

A shy, nocturnal species so best maintained in a dimly-lit aquarium. Provide plenty of hiding places in the form of clay flowerpots, lengths of plastic piping, driftwood tangles etc. Plants are not essential but useful in reducing the amount of light hitting the bottom of the tank as well as offering cover.

If you're keeping multiple specimens or other similarly-sized catfishes try to arrange the décor in such a way as to form distinct territories. The heater should also be placed in such a way that it doesn't allow the fish to rest behind or against it. Also note that this species doesn't appreciate strong water flow.

Apparently feeds on small, benthic animals and organic detritus in nature but will accept most aquarium foods.

Small live and frozen fare such as Artemia, Tubifex, bloodworm, etc., is particularly suitable, and high-quality, sinking dried products enriched with Spirulina or other vegetable content should also be offered regularly.

Peaceful with species inhabiting other areas of the tank and has a relatively small mouth so is unable to swallow anything larger than a few millimetres in length.

It may be seen more often if maintained alongside schools of 'dither' fishes, for which good choices include larger rasboras, medium-sized barbs or perhaps the glass catfish Kryptopterus minor.

It is territorial towards other benthic species, especially conspecifics, and males in particular will not often tolerate each other in all but the largest aquaria.

Keep a single male alongside 3 or more females for the best chance of long-term success as this should help reduce the chance of any single individual being targeted by the dominant male.

Males possess a pointed, externally visible genital papilla located just anterior to the anal fin and noticeably longer barbels, while sexually mature females are normally slightly larger-bodied.

Unrecorded in captivity as far as we know. In nature adults move into temporarily-flooded areas at the onset of the wet season to spawn.

The vernacular name 'lancer' is derived from the extended dorsal spine possessed by several members of the genus, which currently contains 7 species.

Among them B. majusculus is most similar to B. macracanthus and B. vaillantii but can be told apart from both by possession of longer pectoral-fin spines (length 15.8 - 20.7 % SL vs. 11.5 - 16.2 %), from the former by possession of a larger adipose fin (length of base 46.0 - 50.7 % SL vs. 38.8 - 45.8 %), plus deeper caudal peduncle (depth 7.1 - 7.5 % SL vs. 5.6 - 7.0 %), and from the latter by possession of a longer dorsal-fin spine (length 24.4 - 32.5 % SL vs. 18.2 - 21.9 %), a less-deep head (depth 14.0 - 16.1 % SL vs. 16.2 - 19.0 %) and deeper adipose-fin (depth 9.9 - 10.5 % SL vs. 8.2 - 9.5 %).