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.

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.