Gastromyzon spp. are obligate dwellers of swift, shallow streams containing clear, oxygen-saturated water and have been recorded from sea level to 1350 m amsl throughout hill regions of Borneo.

They typically inhabit riffles and runs and are often found above or below cascades and waterfalls.

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

The identity of this species was unclear for a number of decades prior to its redescription by Ng and Kottelat (2013).

The confusion originated with Brittan (1954) who misidentified specimens of R. tornieri as R. dusonensis and was exacerbated by Alfred (1963) who concluded that the holotype of R. dusonensis was conspecific with R. myersi.

This species is included in the Betta unimaculata complex of closely-related species within the genus, of which members share the following set of characters: body long and slender with depth at dorsal fin origin 18-25 % SL; head large and blunt with width 19-24 % SL; long maxilla and lower lip with distance from tip of lower jaw to posterior end of maxilla 27-54 % HL; caudal-fin rounded in shape, occasionally with elongated median rays; pelvic-fin short and filamentous; dorsal and anal fins relatively pointed.

Endemic to southern Kalimantan, the Indonesian portion of Borneo where it’s been recorded from several river systems including the Kapuas, Kepayang, Barito and Kahajan. Type locality is given as ‘Canal along the highway from Oelin to Bandjermasin, about 15 kilometers from Bandjermasin, Borneo.’

Often referred to as the ‘rhomb’ or ‘rhombo’ barb and included in a group of closely-related, similar-looking congeners which also includes…

P. apogon has formerly been placed within the genera Kryptopterus, Micronema (Rainboth, 1996) and more recently Phalacronotus (Ferraris, 2007) and is an important food fish across much of its native range.

It’s very similar to P. micronema but can be told apart by its longer head (HL fits 4.6± 5.3 times in…

This species is distinguished from its Australian congeners S. jardinii and S. leichardti by possessing a lower number of lateral line scales (21-26 vs 32-36).

It occurs naturally in a number of colour forms of which three were elevated to distinct species status in 2003, but the current majority view is that all represent S. formosus pending a detailed review. Kottelat (2013) mentions that the red form may…

Appears to be endemic to southwestern Borneo though occurence records are scant. Type locality is ‘Bandjarmasin’, a port town in the Indonesian province of Kalimantan Selatan (South Kalimantan), and following Kottelat (1991) it’s range extends westwards as far as the Jelai Bila river basin, near the town of Sukamara, where it’s said to occur sympatrically with the congener B. merah.

Boraras was erected in 1993 in order to separa…

This is the most commonly-encountered representative of the genus in the aquatic trade though is by no means common. As in other members of the genus body colouration is highly variable, even among individuals collected from a single locality, although a few useful regularities have been observed which can be used to distinguish certain species. This is thought related to the fact that Acrochordonichthys spp. periodically shed their skins and appear paler post-moulting.

A. rugosus lends its …

Aggressively territorial and incompatible with other fishes in all but the largest public installations and even then may attack its tankmates.

It’s also one of few freshwater fishes that appear unafraid of humans meaning care must be exercised when performing maintenance.