Taxonomy & naming
Inlecypris maetaengensis was described by Fang in 1997 from specimens collected in the Nam Mae Taeng River, Mae Nam Ping tributary drainage, northern Thailand. The original description placed it in Danio — the broad catchall genus for small Asian cyprinids at the time — as Danio maetaengensis Fang, 1997.
Subsequent revisions reshuffled the species twice. A first reclassification moved it into Devario, a genus that had been segregated from Danio to hold the larger, more elongate danionine fishes of mainland Asia. Kottelat (2013) then erected or redefined Inlecypris and transferred the species to that genus, yielding the current valid combination Inlecypris maetaengensis (Fang, 1997) as accepted by the Catalog of Fishes (Eschmeyer, CAS). The parenthetical authority signals that the species has moved from its original genus. Synonyms still in circulation include Danio maetaengensis Fang, 1997 and Devario maetaengensis (Fang, 1997); FishBase continues to index the species under Devario.
The species epithet maetaengensis is a Latinised toponym derived from Mae Taeng, the river and district in Chiang Mai Province that form the type locality.
Morphology
Inlecypris maetaengensis is a streamlined, moderately elongate cyprinid reaching 2 in standard length, with a total length approaching 2 in. The body plan is typical of fast-water danionines: a fusiform profile, slightly compressed flanks, and a subterminal to slightly upturned mouth suited to mid-water or surface feeding. Like related species in Inlecypris and Devario, it carries small barbels.
Detailed colour description from wild-caught specimens is sparse in available sources, but as a member of the danionine assemblage it is likely laterally marked with horizontal stripes or longitudinal patterning on a silvery or pale gold ground — a pattern common to its nearest relatives in the Chao Phraya drainage. Published photographs are uncommon given its rarity in the trade and limited collection record.
Habitat
The species is recorded exclusively from the Nam Mae Taeng River and its immediate tributary drainage in the upper Chao Phraya basin, northern Thailand — a geographically narrow endemic range. The type locality lies in the upland zone north of Chiang Mai at modest elevation.
Habitat at collection sites is characterised by clear, fast-flowing water over substrates of sand, gravel and rock with little or no aquatic macrophyte growth — a classic, well-oxygenated hill-stream environment. Current is moderate to swift. Water parameters recorded from the drainage span a broad range: pH 6.0–8.0, hardness roughly 36–268 ppm (approximately 2–15 °dGH), and temperatures 68–79 °F, consistent with a cool, seasonally variable montane stream system rather than a lowland tropical river.
Feeding
Inlecypris maetaengensis is an omnivore with a preference for small animal prey. In its fast-flowing hill-stream habitat the diet likely centres on aquatic and terrestrial insects and their larvae, small crustaceans and other invertebrates carried by the current — the prey base typical of stream-dwelling danionines.
In aquarium settings, captive specimens accept a variety of live and frozen foods. Bloodworms (chironomid larvae), Daphnia and Artemia (brine shrimp) are reported to be taken readily, and good-quality small flake or pellet foods are generally accepted. Feeding behaviour is active and mid-water to surface-oriented, as expected for a swift cyprinid.
Mating
Like all danionines, Inlecypris maetaengensis is an egg-scattering, non-guarding spawner. There is no nest-building, no pair bond and no parental care. Courtship follows the typical danio pattern: a ready male pursues a gravid female persistently through the water column, and the pair release eggs and milt together in a brief spawning embrace.
In nature, spawning in hill-stream cyprinids is often linked to seasonal cues — temperature shifts, rainfall and rising water levels associated with the monsoon. No detailed field observations of wild spawning behaviour for this species have been published; the above account is inferred from close relatives with which it shares the same subfamily and reproductive guild.
Breeding
Captive breeding has been achieved by aquarists working with the species, and the reproductive pattern is consistent with other fast-water danionines. Spawning occurs readily once fish are in good condition: eggs are scattered freely and the spawning act is typically completed within 24 hours of pairing. Eggs hatch in approximately 24–36 hours at water temperatures in the lower end of the species' range.
No parental care is given at any stage — adults will consume eggs and newly hatched larvae if not removed. Standard danio breeding protocol is appropriate: a separate spawning vessel with a fine mesh, marbles or dense plant cover to protect eggs from predation by the parents, removal of adults after spawning, and rearing of larvae on infusoria followed by newly hatched brine shrimp. Cool, well-oxygenated water conditions matching the species' natural habitat should be maintained throughout.
In the aquarium
Inlecypris maetaengensis is rare in the aquarium trade and encountered mainly by specialist hobbyists willing to seek it out. Its hill-stream origin makes it unsuitable for the standard warm tropical community: it needs cool, oxygen-rich, briskly flowing water — a temperature range of 68–79 °F, pH 6.0–8.0, and moderate hardness — combined with strong filtration and vigorous surface agitation to maintain dissolved oxygen at levels the species requires.
A tank of at least 20–25 US gal is recommended. Decor should reflect the natural habitat: sand and gravel substrate, smooth rocks and minimal or no rooted aquatic plants (which are absent in its fast-flow environment). Appropriate companions are other cool-water, current-loving fishes that share similar requirements. Like all small shoaling cyprinids it benefits from being kept in a group of six or more, which reduces stress and brings out natural schooling behaviour. It should not be housed with tropical species that need temperatures above 79 °F.
Conservation
Inlecypris maetaengensis is classified as Data Deficient on the IUCN Red List (assessed 2012). The designation reflects the limited information available on population size, trends and the full extent of its range rather than a judgment that it is not at risk. The species is known from a restricted area within the Mae Nam Ping drainage of northern Thailand, a geographically narrow endemic range that inherently limits its resilience to local threats.
Pressures on clear hill streams in the upper Chao Phraya basin include agricultural water extraction, deforestation in upland catchments (which raises sedimentation and water temperature and reduces the fast, clear flows this species depends on), and infrastructure development. Collection for the aquarium trade appears to be modest given the species' scarcity in commerce, but any trade pressure on a highly range-restricted fish deserves monitoring. A formal assessment with adequate survey data would likely clarify whether Data Deficient status should be elevated.