It is thought to have been extirpated from the Chao Phraya and Mae Klong rivers, Lake Songkhla, and the entire island of Java due to a variety of anthropogenic factors, and the Mekong populations have also been drastically reduced. In particular, it is sensitive to pollution and gillnetting, and is heavily overfished.

The five species which currently comprise Luciosoma can be distinguished by elements of colour pattern. Popta described the colour pattern of L. pellegrinii as follows: body colour olive dorsally, with dark-edged scales, yellow ventrally; a lateral series of dark spots on the flank forming a midlateral band which extends onto the opercle but not the head; 4-8 blackish-brown, distinctly-separate spots on the lateral line; fins yellow; dorsal and anal fins with a blackish-brown band; anterior half of some pectoral-fin rays blackish-brown…

Apparently native to Peninsular Malaysia plus the Greater Sunda Islands of Borneo, Sumatra, and Java. Reports of this species from the Mekong, Chao Phraya, and other rivers in Indochina refer to the congener L. rubripinna (see ‘Notes’).

Type locality is ‘Indonesia: Borneo: Kalimantan Selatan: Banjarmasin’.

Different populations vary in appearance somewhat (see image of Salween specimen for example), and L. leptocheilus may turn out to represent a group of closely-related species rather than a single taxon. The population from the Cambodian Mekong has been considered to represent a distinct species, Labiobarbus lineatus, although that name is currently a synonym of L. leptocheilus following Kottelat (2013). It is widely used in the ornamental trade, however.

L. chrysophekadion is also known as ‘black sharkminnow’. It continues to be available in the ornamental trade despite its patent unsuitability for the home aquarium, and an albino form has been selectively bred for the purpose.

It can be distinguished from other members of the genus by the following combination…

Substrates are generally composed of gravel, rocks, boulders or bedrock carpeted with a rich biofilm formed by algae and other micro-organisms.

At a habitat in the Mendawai river basin in central Kalimantan, H. borneensis was collected from a foothill stream running swiftly over a rock and gravel substrate with clear water of pH 6.4.

In the Mekong, it has been observed to migrate upstream from Phnom Penh to Khone Falls between November and February, returning downstream between May and August. The downstream migration ends in the Mekong delta area in Vietnam, where the fish remain until the floods reach their peak in October and November. These lower Mekong migrations mostly comprise juveniles and sub-adults, whereas above Khone Falls…

Given its wide natural range it seems logical that this species is or has been available in the aquarium trade, although its correct name may never have been applied.

It is told apart from congeners by the following combination of characters: two pairs of barbels; a continuous midlateral stripe from the tip of the snout to the base of the caudal-fin, with a conspicuous small blotch at the posterior extremity, faintly marked on the caudal-fin; a faint mark between the anus and the anal-fin origin in juveniles; a narrow mouth.

The genus Sundasalanx is distributed throughout much of Southeast Asia and currently comprises seven species which have primarily been distinguished on the basis of oral and dental morphology, gill rakers and eye size. S. microps possesses 0-3 small conical teeth on ceratobranchial 5, 0-2 minute gill rakers on the first arch and a small eye measuring less…

This species is clearly unsuitable for the home aquarium given its eventual size and natural behaviour, and we know of only a handful of private aquarists with the facilities required to house it long-term.

The grouping currently contains four species but is in urgent need of review with a number of additional taxa thought to exist and B. yarrelli possibly representing a synonym of B. bagarius.