Taxonomy & naming
Leporinus nigrotaeniatus was described by the Scottish naturalist William Jardine in 1841 and placed, as with all headstanders of this genus, in the family Anostomidae within the order Characiformes. The genus Leporinus — Latin for "hare-like," a reference to the split, incisor-bearing upper lip shared across the group — remains large and taxonomically active; the Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for which combinations are currently valid, and species boundaries within Leporinus and the closely related genus Anostomus have been revised repeatedly as material is re-examined.
The species epithet nigrotaeniatus is built from the Latin niger (black) and taenia (band, ribbon), describing the dark longitudinal stripe that runs the length of the body — the field mark that gives the fish its common trade name, the black-banded or black-lined leporinus. No English common name is standardized in the literature reviewed here; the species is most often sold and discussed under its scientific name.
Morphology
Leporinus nigrotaeniatus has the elongated, torpedo-shaped body typical of the genus: a moderately compressed trunk, a small subterminal mouth armed with the incisor-like teeth that give Leporinus its name, and a single bold black stripe running from behind the head to the base of the tail against a silvery-to-golden ground colour. FishBase records a maximum length of 15.5 in, a size that some aquarium-trade sources understate — a handful of retail profiles cite a much smaller "aquarium size" around 8 in, but that figure describes juveniles at the point of sale, not the adult the fish will become in a well-run tank.
As with other headstanders, the body plan is built for its distinctive feeding posture rather than for open-water speed: fish routinely tip into a steep, head-down angle to graze surfaces, and the fins are moderate in size rather than the elongated, showy fins seen in some related anostomids.
Habitat
The species is native to the Rio Negro basin and coastal river drainages of Guyana in northern South America, a region dominated by the Negro's characteristically dark, tannin-stained blackwater as well as clearer coastal streams. FishBase reports a temperature range of roughly 73–79 °F and a pH range of 6.0–7.8, spanning the soft, acidic blackwater conditions typical of the Negro system through to milder, closer-to-neutral water in the coastal drainages — a wider chemistry tolerance than a strict blackwater specialist.
Within these rivers the fish associates with submerged wood, root tangles and marginal vegetation, the same structure that supports the algae and biofilm it grazes; flooded-forest and flooded-margin habitat during high water likely extends its foraging range, consistent with the seasonal flood-pulse dynamics that shape fish communities across the wider Amazon-Guiana region.
Feeding
Leporinus nigrotaeniatus is a grazer and aufwuchs feeder in the classic headstander mould: it tips into its head-down posture to rasp algae and biofilm from wood, rock and other submerged surfaces, supplementing this with insects, crustaceans and other small invertebrates picked from the same surfaces, and with plant material. Aquarium-husbandry sources describe it as omnivorous, taking plant matter, insects and crustaceans readily in captivity.
In the aquarium this translates into a fish that needs a genuinely vegetable-forward diet — algae wafers, blanched vegetables, spirulina-based foods — topped up with occasional protein such as small live or frozen invertebrates. Soft-leaved aquarium plants are at real risk from a grazing headstander this size, and keepers should expect and plan for some plant damage rather than be surprised by it.
Mating
No detailed courtship description for Leporinus nigrotaeniatus was found in the sources consulted. Headstanders as a group are not known for elaborate pair-bonding displays; where breeding has been observed in related Leporinus and Anostomus species, spawning is associated with rising water and dense, weedy cover rather than a distinct courtship ritual, and there is no reliable external sexual dimorphism reported for this species — sex is not readily determined by colour or fin shape.
Breeding
Leporinus nigrotaeniatus is, so far as the available sources describe it, an egg-scatterer: pairs spawn over densely grown, weedy areas of the habitat, releasing eggs among the vegetation with no parental care afterward. This matches the pattern documented for the genus generally, where a handful of Leporinus and Anostomus species have been bred incidentally in aquaria or on fish farms, but the group as a whole is rarely bred intentionally in the home hobby.
There is no aquarium-breeding account for this specific species in the material reviewed here, and it should be treated as essentially unbred in home aquaria — a keeper acquiring this fish is very likely acquiring a wild-collected or farm-collected specimen rather than a captive-bred one.
In the aquarium
The single fact a prospective keeper needs to internalise is the real adult size: 15.5 in, not the 8 in sometimes quoted for shop-sized juveniles. That calls for a large, long aquarium with open swimming space and robust filtration to match a big, actively grazing fish's bioload, plus driftwood and rockwork to give it natural grazing surfaces. Aquarium-husbandry sources describe the species as gregarious and generally peaceful toward other fish but capable of real territoriality toward its own kind, which fits the wider pattern in Leporinus and Anostomus: several species in this genus group are documented fin-nippers and become increasingly territorial with age and size, and a spacious, well-furnished tank with visual breaks reduces both problems.
Soft-leaved plants should be considered at risk given the species' grazing habits — hardscape (wood, rock) stands up far better than a planted layout. Given the lack of any aquarium-breeding record, hobbyists should assume this species will not be bred at home and should source stock accordingly.
Conservation
The IUCN Red List assesses Leporinus nigrotaeniatus as Least Concern, an assessment dated December 2020, reflecting a wide native range across the Rio Negro basin and Guyana's coastal drainages without evidence of significant population decline. The species does not appear to face the intense, documented pressures reported for some other South American food or ornamental fishes, though the broader conservation concerns for the Rio Negro system — including mining, deforestation and hydrological change across the wider Amazon-Guiana region — remain relevant long-term context for any species native to it.