Nematabramis species are found a variety of habitat-types, from swiftly-flowing affluent streams to pools, lakes, and degraded swamps. Based on the available collection records juveniles and subadults of N. everetti display a preference for fast-moving water whereas adults are found in deeper, slower stretches of minor tributaries.

Predominantly a riverine fish preferring clear, well-oxygenated, running waters with substrates of sand, gravel, rock or mud, and apparently displays a preference for deeper, slower-moving stretches.

In Sabah such habitats typically flow through tropical forest, although in recent years freshwater habitats throughout much of the state have been extensively modified by human activity such as conversion to palm or rubber plantations.

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.

This species can be most easily distinguished from other members of the genus by its colour pattern which consists of a blackish midlateral stripe extending from the tip of the gill opening to the middle of the caudal-fin base, which is separated from the dark brown dorsum by a pale yellowish brown stripe. This differs from the pattern seen in other Crossocheilus species with a black midlateral stripe in which the the dorsum is olive brown and much paler than the midlateral stripe, there is no yellow stripe between the dorsum and the black stripe, and the black stripe extends to the tip of the snout.

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 variable in terms of colour. Large adults may be bright green, orange or barred but are apparently capable of changing from barred to plain in just a few seconds.

These different forms have been recorded in the same natural habitats, and some individuals also possess prominent nuptial tubercules covering much of the body.

B. sabanus is very similar to B. doriae and these two are easily confused. However in B. doriae most of the first-dorsal-fin and two-thirds of the pectoral-fin are black while in B. sabanus the last one or two rays of the first dorsal-fin are colourless and less than half of the pectoral-fin is black.

In addition there are usually smaller dark ‘saddles’ betw…

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.