Type locality is ‘Central Sumatra, Indonesia’, with additional records existing from Cambodia (Mekong drainage), Peninsular Malaysia (Perak River), Sumatra (from the Siak River, Riau province to the Musi River, South Sumatra (Sumatera Selatan) province) and Borneo (south and westwards from the Belait river basin in Brunei Darussalam to the Sambas drainage in West Kalimantan (Kalimantan Barat) province, Indonesia and probably in Sarawak, Malaysia).

The genus Barbonymus was erected by Kottelat in 1999 and contains former members of Barbodes from southeast Asia. The type species is B. schwanenfeldii and currently there exist only three other representatives; B. altus, B. collingwoodii and B. gonionotus.

The latter two are rare in the hobby although an SF member has kept B. gonionotus in the past so they are worth looking out for if you harbour an…

The water at the type locality is described as ‘clear and fast-flowing over a rocky substratum’. H. parclitella was observed in shallow water among the rocks, and sympatric species included Garra cambodgiensis, Neolissochilus soroides, Poropuntius smedleyi, ‘Puntius‘ binotatus, Homaloptera nebulosa and Amblyceps mangois.

This species is also referred to as ‘Asian knifefish’ or ‘ghost knifefish’ in the aquarium trade in the aquarium trade but arguably has no place in the ornamental hobby given its adult size and specialised requirements.

It is sometimes confused with the African species Xenomystus nigri but is easily told apart by its larger adult size and presence (vs. absence) of a dorsal fin.

D. polota is sometimes referred to as D. quadrifasciatus (Sevastianov, 1809) but the original name of the latter, Chaetodon quadrifasciatus Sevastianov, 1809, is a junior primary homonym of the older Chaetodon quadrifasciatus Bloch & Schneider 1801, thus Coius polota Hamilton, 1822 takes precedence.

C. micropeltes is also referred to as ‘Indonesian’, ‘red’, or ‘redline’ snakehead, the latter names in reference to the appearance of juveniles which often appear in the ornamental trade despite its unsuitability for home aquaria. It is somewhat hyperbolised in the media as a fearsome, invasive “monster” fish with a reputation for killing more fish than it can eat, and even the occasional human, although in reality…

In aquarium literature this species is also referred to as ‘fine scaled tiger fish’, ‘Indonesian tiger fish’, ‘Sumatran tiger fish’, ‘Indo datnoid’, and ‘Indo dat’. The common name of ‘tiger fish’ is also used in reference to the African alestid genus Hydrocynus, and the more appropriate ‘tiger perch’ was suggested by Roberts and Kottelat (1994).

It can be told apart from other members of the B. pugnax group by the following characters: chin bar present; no complete second postorbital stripe on opercle; presence of transverse bars in caudal-fin of males; caudal-fin in males broadly lanceolate; opercle scales iridescent blue; anal-fin with reddish subdistal band and black margin; caudal-fin without dark margin; 25-28 anal-fin rays; 28-31 lateral scales; 11-12 postdorsal scales; length of pelvic fins 26.6-43.8 % SL; length of head 27.5-35.2 % SL; inter-orbital width 32.4-53.0 % HL.