Taxonomy & naming
Danio catenatus was described by Sven O. Kullander in 2015, placing it within the genus Danio — the true danios, a genus of slim, active, horizontally patterned cyprinids distributed across South and Southeast Asia. The Catalog of Fishes (Eschmeyer, CAS), the authority for valid names, records the valid combination as Danio catenatus Kullander, 2015.
The genus Danio has undergone considerable revision. Earlier authors split smaller species into a resurrected Brachydanio, while others shuffled members between Danio and the closely related Devario; the celestial pearl 'galaxy rasbora' was moved into Danio as D. margaritatus. Current Catalog of Fishes placement retains D. catenatus in Danio. No common name has been formally established in the hobby literature for this species.
Morphology
Danio catenatus reaches a maximum recorded size of approximately 2.5 in standard length, making it somewhat larger than many of its congeners. FishBase records 11–13 dorsal soft rays and 17–18 anal soft rays, with a vertebral count of 36–38 — meristic data consistent with a robust, active cyprinid.
Like other true danios it is elongate and laterally compressed, with a slightly upturned mouth suited to feeding at and near the surface. The specific epithet catenatus (Latin: 'chained') alludes to a patterned chain-like marking along the flanks, though detailed colour descriptions from living specimens in the aquarium trade are sparse given the species' rarity in the hobby.
Habitat
The type locality of Danio catenatus is a small, clear-water forest stream in the Thandwe Chaung drainage of Rakhine State, on the western slope of the Rakhine Yoma mountains in western Myanmar. The substrate at this locality is pebble, rock and gravel — a clean, well-oxygenated current-swept environment typical of hill-stream cyprinids.
The Rakhine Yoma is a north–south range separating the Irrawaddy basin from the narrow coastal drainages that flow westward into the Bay of Bengal. D. catenatus is a species of these smaller, isolated western-slope drainages rather than the larger river systems of interior Myanmar. Like other hill-stream danios it inhabits clear, moderately cool water; genus-typical parameters for the region run around pH 7.0–7.8 and temperatures of roughly 68–77 °F, reflecting upland forest streams rather than the warm, turbid lowland habitat of more familiar species.
Feeding
Danio catenatus is an omnivore, as are all members of the genus. In clear, fast-flowing hill streams the diet is dominated by small invertebrates — aquatic insect larvae, small crustaceans and terrestrial insects that fall onto the water surface — supplemented with algae and organic detritus.
In captivity, danios of this type accept all standard aquarium foods: quality flake and small sinking or floating granules, with live and frozen items such as daphnia, chironomid larvae and brine shrimp maintaining peak condition. Given its hill-stream origins, this species may particularly appreciate a varied diet with regular live or frozen invertebrate foods.
Mating
Danio catenatus, in common with all members of the genus, is an egg-scattering, non-guarding spawner. There is no nest construction, no bubble-nest and no mouthbrooding. Spawning is stimulated by rising temperatures, water changes and the presence of fine-leaved vegetation or clean substrate.
A driving male pursues a gravid female through vegetation or close to the substrate, and the pair briefly press together as eggs and milt are released simultaneously. The encounter is fleeting — there is no sustained pair bond, and the adults will readily consume the eggs they have just scattered if they encounter them.
Breeding
Like its congeners, D. catenatus scatters adhesive eggs over plants, moss or clean gravel substrate, after which the adults provide no parental care whatsoever. Breeding in captivity would follow the standard danio protocol: a separate spawning tank with a mesh or layer of large pebbles to protect scattered eggs from the parents, a slight temperature increase to the upper end of the natural range, and the addition of fresh soft water to simulate natural seasonal cues.
Eggs are expected to hatch within two to three days at suitable temperatures, with free-swimming larvae requiring fine live foods such as infusoria followed by newly hatched brine shrimp. Captive breeding records for this species are not well documented in hobby literature given its rarity in the trade.
In the aquarium
Danio catenatus is uncommon in the aquarium trade and not widely kept. For hobbyists who do obtain it, its hill-stream origins dictate the ideal setup: a longer tank with strong water movement and high oxygenation, a substrate of smooth pebbles or fine gravel, and water parameters on the cooler, cleaner end — around 68–77 °F, pH 7.0–7.5, soft to moderately hard water. Warm, stagnant or poorly oxygenated conditions would be detrimental.
As a shoaling cyprinid it should be kept in groups of at least six individuals. Its larger size relative to many danios means it can be housed with similarly active, appropriately sized tankmates. It is unlikely to trouble other occupants but its speed and energy may unsettle very slow or long-finned companions. Given its rarity, acquiring captive-bred specimens from specialist suppliers is strongly preferred over wild-caught fish.
Conservation
Danio catenatus has not been formally evaluated by the IUCN Red List — it was described in 2015 and as of 2026 remains unassessed (Not Evaluated). Its known range is narrow, confined to the Thandwe Chaung drainage on the western slope of the Rakhine Yoma, western Myanmar.
Myanmar's hill-forest streams face significant and growing pressure from deforestation, agricultural expansion, and the loss of riparian forest cover that maintains stream clarity and cool temperatures. Species with restricted ranges in isolated coastal drainages are particularly vulnerable to local disturbance. Until a formal IUCN assessment is completed, the conservation status of D. catenatus remains uncertain, but its habitat specificity and limited known range warrant monitoring.