Taxonomy & naming
Triportheus magdalenae was described by the Austrian ichthyologist Franz Steindachner in 1878, with a type locality in the Magdalena River, Colombia. It belongs to the genus Triportheus, a group of laterally compressed, surface-oriented characins historically placed with the pacus and silver dollars in Serrasalmidae but increasingly treated by modern workers as members of a separate lineage (Triportheidae) within Characiformes; the Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the authority for the currently accepted placement and should be consulted for the most current family assignment. Whatever the family-level bookkeeping, the genus Triportheus itself is stable and well recognised, and this species remains firmly Triportheus magdalenae.
The species is notable biogeographically as the sole representative of Triportheus in the trans-Andean Magdalena system — every other Triportheus species occurs in the cis-Andean drainages of the Amazon, Orinoco, Paraguay-Paraná and the Guianas. That isolation makes T. magdalenae a distinct evolutionary lineage worth conserving in its own right, independent of how common or secure its cis-Andean relatives are.
Morphology
Like other members of its genus, Triportheus magdalenae has a laterally compressed body with a pronounced ventral keel running from the throat back toward the anal fin, an upturned mouth with a protruding lower jaw, and noticeably enlarged, wing-like pectoral fins — features shared across the "hatchet-tetra" Triportheus lineage and associated with feeding and escape near the water's surface. FishBase gives a maximum recorded size of 14 in standard length and a weight around 470 g for the species, which is a substantial size for a characin of this general body plan; specimens documented in trophic-ecology studies from the Magdalena basin, however, have run considerably smaller, in the range of roughly 1.5–5 in standard length, indicating that most individuals encountered in surveys are well short of the recorded maximum.
Colouration follows the typical Triportheus pattern of a bright silver body with a darker dorsal surface, consistent with a fish that spends much of its life in open water near the surface rather than in cover.
Habitat
Triportheus magdalenae is endemic to the Magdalena River basin of Colombia, including the Cauca River (a major Magdalena tributary) and floodplain water bodies such as the El Guájaro reservoir in the lower basin. It is a freshwater, benthopelagic species of tropical rivers and associated floodplain habitats, occupying open, flowing to slow-flowing water rather than densely vegetated margins.
Specific published temperature and pH ranges for this species were not found in the sources consulted; the Magdalena basin is a warm tropical lowland system, and water conditions there are broadly consistent with other Neotropical river characins, but exact figures should not be assumed without a dedicated hydrological source for this species.
Feeding
Triportheus magdalenae is documented as a carnivore with a strong zooplanktivorous bias — one dietary study found zooplankton accounted for roughly 96% of its feeding niche, indicating a narrow, specialised diet rather than the broad omnivory seen in many of its relatives. A trophic-ecology study from the El Guájaro reservoir in the lower Magdalena basin likewise characterises the species as an insectivore/zooplankton feeder within that system.
This specialisation toward small suspended prey is consistent with the species' upturned mouth and surface-oriented body plan, which are well suited to picking zooplankton and small invertebrates from open water rather than grazing substrate or browsing vegetation.
Mating
No courtship or pairing behaviour for Triportheus magdalenae was found in the sources consulted for this account. Data is sparse for this species specifically, and nothing should be inferred from other Triportheus or from unrelated Serrasalmidae without a citable source.
Breeding
Published breeding data for Triportheus magdalenae is not available in the sources consulted here. The species has no established record of captive or aquarium breeding, and no spawning mode, egg type or parental-care behaviour could be confirmed. Rather than assign a breeding strategy by analogy to other characins, this account reports the gap plainly: reproduction in this species should be treated as effectively undocumented pending a dedicated study.
In the aquarium
Triportheus magdalenae is not an established aquarium species, and no aquarium-specific husbandry literature was found for it. Given a documented maximum size of 14 in standard length, any specimen that did reach the hobby would need a substantial, long aquarium with open swimming space and secure covering — Triportheus species are active, surface-dwelling jumpers, and a fish of this size is not a casual community-tank prospect. As with other minor characins from the Magdalena system, this species should be regarded as a scientific-interest or specialist fish rather than a routine trade item, and prospective keepers should not assume it will behave like the smaller, well-documented tetras more familiar in the hobby.
Because this account cannot confirm captive water-chemistry tolerances or dietary requirements from a hobby source, anyone attempting to keep this species should start from its natural Magdalena River habitat conditions and its documented zooplanktivorous diet, offering fine live and frozen foods (daphnia, cyclops, brine shrimp) rather than assuming it will take flake or pellet readily.
Conservation
Triportheus magdalenae is assessed by the IUCN Red List as Least Concern, an assessment dated October 2014, with no documented population decline. As a Magdalena basin endemic, however, its conservation picture is tied to the health of a single, heavily used river system — the Magdalena is Colombia's most important and most human-impacted drainage, subject to damming, agricultural runoff and urban pressure — so a wide range within that basin does not mean the species is free of long-term risk, even though the current formal assessment is not one of concern.
No evidence of significant aquarium-trade collection pressure on this species was found; its conservation profile is shaped by basin-wide environmental pressures on the Magdalena system rather than by targeted harvest.