Taxonomy & naming
Rasbora myersi was described by Martin R. Brittan in 1954, who placed it in the large, ecologically diverse genus Rasbora. The Catalog of Fishes (Eschmeyer, CAS) lists the valid combination as Rasbora myersi Brittan, 1954. No subsequent revision has moved the species to another genus, and the name stands without parentheses — Brittan remains the direct authority.
The genus Rasbora has been substantially reorganised over the past three decades. Kottelat and others carved out several satellite genera — Boraras (miniature Sundaland rasboras), Brevibora, Trigonopoma, Rasboroides, and others — but R. myersi has remained within the core Rasbora group. A 2020 molecular phylogenetic study of Rasborinae confirmed the subfamily's broad Sundaland distribution and its complex internal structure, providing useful context for interpreting the placement of species such as myersi within the lineage.
The species epithet honours Dr George Sprague Myers (1905–1985), the prolific American ichthyologist based at Stanford University who described hundreds of freshwater fish species and contributed foundational work on the systematics of tropical cyprinids.
Morphology
Rasbora myersi is a slender, elongate rasbora reaching a maximum of approximately 3 in standard length — making it one of the larger members of the genus compared with the miniature Boraras-group rasboras of the same region. The body is laterally compressed with a streamlined torpedo profile, and the mouth is terminal and slightly upturned, suited to surface and mid-water feeding.
Coloration in life follows the general rasbora pattern: a silvery or pale golden body with darker pigmentation along the lateral line region and a slim, often faint, horizontal stripe running the length of the flank. Fins are clear to faintly pigmented. As with most rasboras, preserved museum specimens tend to lose the iridescent sheen that makes fresh or living fish more distinctive. Sexual dimorphism is subtle; females are typically deeper-bodied and more rounded in the abdominal region when gravid, while males are slimmer.
Habitat
Rasbora myersi is native to tropical freshwaters of Southeast Asia, with records from Malaysia and Indonesia — placing it squarely in the Sundaland biogeographical zone that encompasses the Malay Peninsula, Sumatra, Borneo and Java. It occupies benthopelagic positions in freshwater streams and peat-swamp forest systems, waters characterised by very low mineral content, high concentrations of dissolved humic acids and tannins from decomposing plant matter, and typically a dark, tea-brown coloration.
These peat-swamp and forest-stream environments are slow-flowing to almost still, shallow and heavily shaded by closed-canopy forest. Water chemistry is typically very soft (1–5 dGH) and acidic (pH 3.0–6.5), with temperatures in the range of 73–82 °F (73–82 °F). Oxygen levels can be low beneath dense leaf litter. R. myersi shares this biotope with a community of other acid-tolerant cyprinids, anabantoids and small catfishes adapted to the chemical extremes of Sundaland blackwater.
Feeding
Like other rasboras of similar size, Rasbora myersi is an omnivore and opportunistic feeder. FishBase records a trophic level of approximately 3.2, consistent with a diet composed largely of small aquatic and terrestrial invertebrates — insect larvae, small crustaceans, worms and other zooplankton — supplemented with plant material, algae and organic detritus encountered at the water surface and in the water column.
In the aquarium the species is undemanding and accepts high-quality flake and micropellet foods. Condition, colour and breeding readiness are all enhanced by a varied diet that includes live or frozen foods such as daphnia, bloodworm, mosquito larvae and brine shrimp — prey types that closely replicate the invertebrate-rich diet of its native peat-swamp streams.
Mating
Rasbora myersi follows the standard rasbora reproductive strategy: it is an egg-scattering, non-guarding spawner with no pair bond and no parental investment beyond the act of spawning itself. When fish are in breeding condition — signalled by a full-bodied female and actively displaying males — a driving male pursues a gravid female closely through vegetation or over the substrate, the pair making brief, close contact as eggs and milt are simultaneously released.
Spawning episodes are short and may be repeated multiple times over a session. There is no nest construction, no territory holding and no subsequent attention to the eggs or hatching larvae. The adhesive eggs settle among fine-leaved plants, moss or on the substrate, where they are largely ignored — or actively consumed — by the spawning adults and other fish in the same water.
Breeding
In the aquarium, Rasbora myersi can be conditioned and bred in a dedicated spawning setup that mimics the soft, acidic peat-swamp water of its native habitat. A small, dimly lit tank with a layer of Java moss, fine-leaved plants or a spawning mop over a dark substrate provides the egg-deposition surface the species naturally uses. Water should be very soft (1–3 dGH), acidic (pH 5.5–6.5) and warm (77–81 °F / 77–81 °F), with gentle filtration through a sponge filter to avoid disturbing the eggs.
A well-conditioned trio — one female and two males — is introduced in the evening; spawning typically occurs the following morning. The adults scatter adhesive eggs among the plants and give no further care; they should be removed after spawning to prevent predation on the clutch. Eggs hatch in 24–48 hours depending on temperature, and free-swimming fry appear a few days later. First foods are infusoria and paramecia, followed by newly hatched brine shrimp and finely powdered commercial fry foods as the young grow.
In the aquarium
Rasbora myersi is a mid-sized, active rasbora suited to a biotope or species aquarium that replicates the soft, acidic conditions of Sundaland peat-swamp streams. A longer tank of at least 23.5–31.5 in provides the horizontal swimming space this shoaling species needs; it should be kept in groups of eight or more, as solitary individuals become shy and spend much of their time hidden. Tankmates, if any, should be species that share the same water chemistry requirements — small barbs, other rasboras, dwarf gouramis, or small loaches from the same region.
Decoration with driftwood, dried leaves (Indian almond, oak), and dense plantings of fine-leaved or floating plants creates the dim, tannin-stained environment in which this fish thrives and shows its best colour. Filtration should be gentle; strong current is uncharacteristic of its native habitat. The water parameters — pH 5.5–6.5, very soft, 73–82 °F (73–82 °F) — must be maintained consistently, as this species is less forgiving of hard alkaline water than more widely traded, domestically adapted rasboras.
Conservation
Rasbora myersi is assessed as Least Concern (LC) on the IUCN Red List, with the most recent assessment recorded in January 2019. Its range across tropical Southeast Asia — including Malaysia and Indonesia — and its association with both freshwater streams and peat-swamp systems means it is not currently considered at immediate risk of extinction at the species level.
However, the peat-swamp forest habitats of Sundaland are among the most threatened ecosystems on Earth. Large-scale drainage for palm oil and pulpwood plantations, peat fires, agricultural conversion and urban expansion have eliminated or severely degraded vast areas of Sundaland peat swamp over the past several decades, and this process continues. Species that depend on these habitats — including many rasboras, fighting fish and other small cyprinids — face growing local pressure even when their overall IUCN status remains Least Concern. Continued monitoring of peat-swamp specialist communities, including R. myersi, is warranted as habitat loss accelerates.