Taxonomy & naming
Devario xyrops was formally described by Fang and Kullander in 2009 in Zootaxa, based on specimens collected from the Thade River drainage near Taunggok in Rakhine State, Myanmar. The species epithet xyrops derives from the Greek xyron (razor) and ops (eye), alluding to a sharply defined supraorbital margin and a notably wide infraorbital process — anatomical features that distinguish it from sympatric or geographically close Devario species. The Catalog of Fishes (Eschmeyer, CAS) records the valid name as Devario xyrops Fang & Kullander, 2009, with no subsequent transfers or synonymisations on record.
The genus Devario comprises the giant danios and allied elongate danionins of South and Southeast Asia, a group long intertwined in the literature with the true danios of genus Danio and with the Indian species once placed in Inlecypris and Microdevario. Devario is defined in the modern sense by Kottelat and broadly follows the arrangement in the Catalog of Fishes, separating the larger-bodied, banded or striped Asian cyprinids from the smaller, often spotted Danio species. Taxonomic scrutiny of the Devario aequipinnatus complex — to which D. xyrops belongs geographically and morphologically — continues, and additional undescribed diversity in the Rakhine drainages is plausible. GBIF places the species in the family Danionidae, order Cypriniformes.
Morphology
Devario xyrops is a moderately large danionin with adult standard lengths of approximately 3 in in females and 3 in in males — measurements placing it firmly in the 'giant danio' size class. The body is laterally compressed and elongate, with the upturned, somewhat oblique mouth and fine barbels typical of the genus.
The colour pattern combines two elements that together are characteristic: anteriorly, a series of four to five dark vertical bars interrupts the lateral field, giving the front half of the fish a 'laddered' look; posteriorly, these resolve into a single wide, dark horizontal band running to the base of the caudal fin, with a paler zone above and below. The sharp supraorbital ridge and enlarged infraorbital process — the features enshrined in the species name — are most apparent in preserved specimens but give live fish a distinctive 'angular' facial profile compared to the rounder-eyed D. aequipinnatus. Fins are generally hyaline to faintly yellowish.
Habitat
The type locality is Yan Khaw Chaung, a small tributary in the Thade River drainage sampled approximately 14 mi along the Taunggok–Pyay road in Rakhine State. At low water the site consisted of a narrow forest river — no more than about 7 ft wide — connected to pools up to 3 ft deep, shaded by riparian vegetation and running over a substrate of sand, gravel and fallen leaf litter. The Rakhine Yoma, an ancient coastal hill range with a strongly seasonal monsoon climate, receives heavy south-westerly rainfall from May to October; these streams swell dramatically in the wet season and contract to chains of pools during the dry.
All known localities lie on the western (Rakhine) slope of this range, isolating D. xyrops hydrologically from the Irrawaddy and Sittaung drainages to the east. The water is likely soft to moderately hard and near-neutral — conditions typical of Myanmar's hill-forest streams — cooler than the lowland rivers at higher elevations and well-oxygenated by the gradient and seasonal spate character of these small watercourses. Seriously Fish reports captive maintenance at 64–79 °F, pH 6.0–8.0, hardness 36–268 ppm, consistent with a cool, seasonally variable hill-stream origin.
Feeding
No dedicated dietary study exists for Devario xyrops, but its morphology and habitat place it solidly in the guild of opportunistic invertivores typical of the genus. The oblique, upturned mouth is adapted for surface and mid-water feeding, and the small forest streams it inhabits are rich in fallen invertebrates, aquatic insect larvae, small crustaceans, and organic detritus carried by the seasonal flow.
In captivity, Seriously Fish reports that D. xyrops accepts quality sinking pellets and floating foods readily, with live and frozen items — bloodworm, Daphnia, Artemia — used to boost condition and breeding readiness. Its active, fast-moving character means it competes well at feeding time, and care should be taken that slower or more timid tankmates receive adequate food if kept in a community setting.
Mating
Devario xyrops is an egg-scattering, non-guarding spawner in the typical danionin manner. There is no pair bond, no nest construction, and no parental investment beyond the act of spawning itself. In the wild, breeding is almost certainly cued by the monsoon: the arrival of heavy rains in May and June raises water levels, lowers temperatures slightly as cool runoff enters the streams, and brings newly flooded margins with fine vegetation and soft substrate — the classic triggers for danio spawning.
A gravid female is pursued closely by one or more males through vegetation or over the substrate; the pair press together briefly and release eggs and milt simultaneously. The scattered eggs receive no subsequent attention from either parent.
Breeding
In the aquarium, Devario xyrops is reported to breed like the broader Devario/Danio group: a dedicated spawning tank with fine-leaved plants, java moss or a mesh over the base keeps eggs from being eaten by the adults. Conditioning on live and frozen foods brings females into spawning condition within a week or two. A small water change with slightly cooler water can serve as a spawning trigger, mimicking the monsoon flush the species experiences in nature.
Eggs are adhesive to moderately adhesive and scattered among plants or over the substrate; Seriously Fish notes that eggs hatch in approximately 24–36 hours at typical temperatures, with fry becoming free-swimming within a few days thereafter. Adults should be removed after spawning to prevent predation of eggs. First foods are infusoria or commercial fry food, transitioning to newly hatched brine shrimp (Artemia nauplii) as the fry grow. No parental care is given at any stage.
In the aquarium
Devario xyrops is infrequently traded — its narrow endemic range and limited export from Myanmar restrict availability — but when obtained it is kept in much the same way as the more familiar Devario aequipinnatus or D. malabaricus. It is an active, fast-moving shoaler that should be kept in groups of eight or more; solitary individuals or small groups become skittish and may harass slower tankmates with constant chasing. A longer tank of at least 35.5 in with open swimming space in the upper and middle water column suits it best.
Water conditions should reflect the cool, clean hill-stream origin: 64–79 °F, pH 6.0–8.0, soft to moderate hardness. Filtration that produces a gentle current is appreciated, and the tank should be well-covered — these are active, powerful swimmers capable of clearing a low rim. Diet is undemanding; a quality dry food supplemented with frozen or live invertebrates keeps fish in excellent condition. Suitable community companions are other similarly sized, robust, fast-moving species that can hold their own in the active flow; avoid slow or long-finned fishes that may be harassed.
Conservation
The IUCN Red List assesses Devario xyrops as Near Threatened (NT), reflecting the combination of a naturally restricted range — confined to the western slope of the Rakhine Yoma in a small number of known drainages — and the ongoing pressures on Myanmar's coastal hill forests. Deforestation for agriculture and logging, extraction of water for irrigation, sedimentation from upland clearing, and periodic collection for the ornamental fish trade all bear on the small forest streams this species depends upon.
The Rakhine Yoma itself retains significant forest cover compared to many of Myanmar's lowland areas, and the streams draining it remain relatively intact; this likely underpins the NT rather than Vulnerable assessment. However, the species' known range is small by any measure, and future habitat loss or a single infrastructure project cutting across the Taunggok road corridor could materially reduce the area of occupancy. No captive-breeding conservation programme is known. Better survey data on the extent of the species' range within the Rakhine drainages would strengthen any future reassessment.