Taxonomy & naming
Striuntius lineatus was originally described by the German ichthyologist Georg Duncker in 1904 as Barbus lineatus, from material collected in Borneo near 2.5°S, 113.5°E. The species passed through the large catch-all genus Puntius — as Puntius lineatus (Duncker, 1904) — before being assigned to the resurrected genus Striuntius under the reclassification of Southeast Asian barbs that followed Pethiyagoda et al. (2012). The Catalog of Fishes (Eschmeyer) recognises the current valid combination as Striuntius lineatus (Duncker, 1904), the parenthetical authority marking the transfer out of Duncker's original genus.
The genus Striuntius accommodates a small group of slender-bodied, striped barbs from Sundaland and neighbouring mainland drainages that were previously treated as Puntius. The synonym chain therefore runs: Barbus lineatus Duncker, 1904 → Puntius lineatus (Duncker, 1904) → Striuntius lineatus (current valid name). Older aquarium literature, field guides and trade sources frequently use the Puntius combination, but that name is no longer considered valid.
Morphology
Striuntius lineatus is a slender, moderately compressed small barb reaching approximately 2 in in standard length. The body is elongate compared with the deep-bodied tiger barb relatives, with a streamlined profile suited to life among emergent and submerged vegetation in still or sluggish water. The flanks are pale to silvery, marked by the fine horizontal longitudinal stripes from which both the scientific epithet and common name derive.
Sexual dimorphism has not been described in detail for this species; as with many small Southeast Asian barbs, females are likely somewhat deeper-bodied and more rounded when gravid. Detailed osteological or colour data specific to Striuntius lineatus are sparse in the available literature.
Habitat
Striuntius lineatus inhabits peat swamps, blackwater streams and still or slow-moving open waters with standing water and submerged grasses across Borneo and peninsular Malaysia. It is characteristically found in clear blackwater — the deeply tannin-stained, humic-acid-rich water typical of lowland Sundaland peat-swamp ecosystems — where pH values may fall well below neutral.
Seriously Fish records a pH range of approximately 4.0–7.0 and a hardness of roughly 18–179 ppm (very soft to moderately soft) for the habitat, with water temperatures of 68–79 °F. These parameters reflect the extreme softness and acidity of Sundaland peat-swamp water, which is among the most chemically distinctive freshwater habitat type in Southeast Asia. The species is benthopelagic and tends to occupy mid-water positions among submerged plants and riparian vegetation.
Feeding
Striuntius lineatus is omnivorous. In its natural habitat it consumes a broad range of small food items including diatoms, algae, organic detritus, small insects, worms, crustaceans and zooplankton, in keeping with the feeding ecology of most small barbs occupying vegetated, slow-water environments.
In the aquarium the species accepts a range of small prepared and live foods, though one source notes that it does not accept freeze-dried foods well. Offering small live and frozen invertebrates — bloodworm, daphnia, brine shrimp — alongside quality micro-pellets or fine flake provides a diet close to its natural intake and supports good condition.
Mating
Like all barbs, Striuntius lineatus is an egg-scattering, non-guarding spawner. Breeding in the wild has not been formally documented, but the reproductive biology follows the general pattern of the group: a driving male pursues a gravid female through fine-leaved vegetation or over the substrate, and eggs and milt are released together in brief, close contact between the pair.
No pair bond is formed, no nest is built, and no territory is defended beyond the transient pursuit of spawning. Adults give no parental care to eggs or fry, and — as with virtually all barbs — are likely to consume scattered eggs if they encounter them.
Breeding
Spawning of Striuntius lineatus in the wild is unrecorded in the available literature. Given its peat-swamp habitat, captive breeding attempts typically replicate soft, acidic blackwater conditions — very low hardness and pH in the range of 4.5–6.5 — with fine-leaved plants or spawning mops to receive the adhesive, scattered eggs and a mesh bottom layer to separate eggs from the adults before they are consumed.
The reproductive pattern — egg-scattering with no parental care — is uniform across the barbs, and the general procedure of conditioning a group on live foods, allowing spawning in a planted, shallow tank, removing the adults afterwards, and raising the larvae on infusoria followed by newly hatched brine shrimp is expected to apply here. Fecundity and incubation data specific to this species are not recorded in the accessible literature.
In the aquarium
Striuntius lineatus is an uncommon but occasionally available species in the specialist aquarium trade. As a blackwater fish from peat-swamp habitats, it is best kept in soft, acidic water that mimics its natural environment: temperatures of 68–79 °F, pH in the region of 4.5–7.0, and very low to low hardness. Dark substrate, tannin-stained water (achieved with dried leaves, peat filtration or driftwood) and subdued lighting approximate its natural conditions and tend to bring out the best behaviour and colour.
It is a social, mid-water shoaler that should be kept in groups of six or more; solitary individuals or very small groups are reported to behave differently and show less natural behaviour. One source notes it does not accept freeze-dried food well, so a diet of small live and frozen invertebrates alongside fine dry food is preferable. It is peaceful and not a candidate for boisterous community tanks; appropriate tankmates are small, quiet fishes tolerant of similarly soft, acidic conditions.
Conservation
Striuntius lineatus is assessed as Least Concern (LC) on the IUCN Red List, with the most recent assessment recorded in 2020 via FishBase. The species has a range spanning Borneo and peninsular Malaysia and is described as common in its preferred clear blackwater habitats, with no evidence of major range-wide decline at the time of assessment.
The primary long-term concern for this species, as with the majority of the Sundaland peat-swamp fauna, is the accelerating loss and degradation of lowland peat-swamp ecosystems across Borneo and peninsular Malaysia through drainage for agriculture (particularly oil palm), peat fires, logging and pollution. Peat swamps are among the most threatened freshwater habitats in Southeast Asia, and species tightly associated with them — including Striuntius lineatus — face increasing habitat pressure even where current population data suggest broad abundance.