Taxonomy & naming
Moenkhausia lineomaculata was described in 2015 by Fernando Dagosta, Manoela Marinho, and Ricardo Benine from type material collected in the upper rio Juruena, a major tributary of the rio Tapajós system in Mato Grosso state, central Brazil. The description was published in Zootaxa. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records the valid name as Moenkhausia lineomaculata Dagosta, Marinho & Benine, 2015; the species has not been moved to another genus and the authority is not parenthetical.
The genus Moenkhausia Eigenmann, 1903 is one of the largest in Characidae, encompassing many of the familiar tetras of the ornamental trade including the red-eye tetra (M. sanctaefilomenae) and the glass tetra (M. oligolepis). Dagosta et al. placed M. lineomaculata within the M. oligolepis complex on the basis of shared meristics and the characteristic partial-to-full red upper eye, and it is most readily distinguished from its close relatives by the reticulated flank pattern. The relationship between M. lineomaculata and the commercially popular red-eye tetras was noted soon after the description was published, prompting brief hobbyist interest.
Morphology
Moenkhausia lineomaculata reaches approximately 2.5 in standard length (SL) according to FishBase, placing it toward the larger end of the M. oligolepis complex. The body is moderately compressed and fusiform, typical of open-water schooling characids, with the fin complement and general proportions characteristic of Moenkhausia.
The distinguishing feature is the flank pattern: scales along the sides are individually outlined by dark margins, producing a reticulated or net-like appearance over most of the body. Superimposed on this reticulation is a longitudinal series of aligned dark spots — the character reflected in the species name — running from roughly mid-flank toward the caudal peduncle. That peduncle carries a conspicuous wide dark blotch, preceded anteriorly by a lighter or pale zone, a combination that differentiates M. lineomaculata from all known close relatives. The eye shows the partial bi-coloration typical of the complex: the lower portion bluish and the upper portion orange to red. No common name has been formally established for the species.
Habitat
The type locality and only confirmed range of Moenkhausia lineomaculata is the upper rio Juruena basin, part of the rio Tapajós watershed, in Mato Grosso, Brazil. FishBase characterises the species as freshwater, tropical, and benthopelagic — occupying the lower to middle water column over substrates typical of Amazonian headwater rivers.
The Juruena drainage flows across the Cerrado-Amazonia transition zone and is characterised by clear, warm, moderately soft to slightly acidic water depending on local geology. Regional Amazonian headwaters where related Moenkhausia species occur typically show temperatures in the range of 72–82 °F and pH values between 6.0 and 7.5, though specific physico-chemical data for M. lineomaculata's precise habitat have not been published in accessible sources. As a schooling characid it very likely occupies the mid-water zone of rivers and streams, taking shelter among riparian vegetation in the manner of its congeners.
Feeding
No dietary study specific to Moenkhausia lineomaculata has been published. FishBase assigns the species a trophic level of 3.4, consistent with an omnivorous or weakly carnivorous feeding strategy. This places it in the same trophic bracket as its close relatives M. oligolepis and M. sanctaefilomenae, which in the wild consume small invertebrates, zooplankton, insect larvae, and plant material opportunistically.
In aquarium conditions, close congeners accept a wide range of prepared and live foods without difficulty. A varied diet of quality flake or micro-pellets supplemented with frozen or live invertebrates such as Daphnia, brine shrimp, and bloodworm is expected to suit M. lineomaculata well, on the basis of its affinity with the red-eye tetra group. Feeding small amounts multiple times daily suits the active foraging style of schooling characids.
Mating
No published account of courtship or mating behaviour for Moenkhausia lineomaculata exists in the available literature. As a member of the M. oligolepis and M. sanctaefilomenae complex, it is expected to follow the egg-scattering, open-spawning strategy universal in that group: males pursue and court receptive females with lateral displays in the mid-water or near fine-leaved vegetation, with spawning triggered by morning light and good conditioning.
In related species such as M. sanctaefilomenae, spawning groups or pairs scatter adhesive or semi-adhesive eggs among fine-leaved plants or over bare substrate, and the adults show no recognition of or care for eggs after release. Competition among males likely drives display intensity, and schools kept together — with multiple males present — produce the most active courtship behaviour, consistent with the pattern seen across the genus.
Breeding
Moenkhausia lineomaculata has not been bred in captivity under documented conditions in the published or hobbyist literature available at the time of writing. The following is inferred by close analogy with M. sanctaefilomenae and M. oligolepis, which are well established in aquarium breeding.
Congeners scatter small, adhesive or lightly adhesive eggs among fine-leaved vegetation or spawning mops. Adults are non-guarding and will consume eggs if left in the spawning tank, so eggs or spawning media are best removed promptly to a separate rearing container. Eggs hatch in roughly 24–48 hours at typical breeding temperatures, and fry become free-swimming after a further day or two, initially requiring very fine live foods such as infusoria or rotifers before accepting newly hatched brine shrimp. Conditioning adults on live and frozen foods ahead of a breeding attempt, and providing a planted tank with a slight temperature rise to the upper end of the tolerated range, is the standard approach for the group. The limited hobby exposure to this species means specific breeding accounts remain lacking; any aquarist who breeds the fish would add genuinely useful data to the record.
In the aquarium
Moenkhausia lineomaculata is rarely encountered in the ornamental trade and, where it does appear, is generally found only among specialist importers sourcing unusual Amazonian species rather than through mainstream retail channels. Its close relationship to the red-eye tetras (M. sanctaefilomenae, M. oligolepis) suggests it would be kept in much the same way: a peaceful, schooling fish requiring a group of at least six individuals, a well-filtered aquarium of adequate length to allow open-water swimming, and tankmates of similar peaceful disposition.
Water parameters for the genus in captivity are typically 72–82 °F, pH 6.0–7.5, and soft to moderately hard water, consistent with Amazonian headwater conditions. A planted aquarium with some open swimming space and subdued or dappled lighting would approximate natural conditions. The reticulated spot pattern and the eye coloration make it an interesting fish for the collector of unusual characids, and the analogies with popular red-eye tetras suggest it should not present serious husbandry challenges for an experienced community aquarist.
Conservation
Moenkhausia lineomaculata has not been assessed by the IUCN Red List. As a species described only in 2015 from a restricted basin in central Brazil, it falls into the large category of recently described Amazonian fishes that have not yet been reviewed under formal conservation criteria.
The upper rio Juruena basin lies within an area of Mato Grosso that has experienced substantial agricultural expansion, particularly soy cultivation and cattle ranching pushing into the Cerrado-Amazonia transition zone. Deforestation, sedimentation, and agricultural runoff are documented pressures on river systems in this region. Whether M. lineomaculata's range is broad enough within the Juruena watershed to buffer against such pressures, or whether it is a genuinely narrow endemic, is not established in accessible literature. In the absence of a formal assessment and with data sparse on distribution and abundance, nothing can be said confidently about the species' conservation status beyond that it is not currently evaluated.