Taxonomy & naming
Cyphocharax magdalenae was described by the Austrian ichthyologist Franz Steindachner in 1878, and the species epithet magdalenae refers to the Magdalena River of Colombia, the drainage from which the type material was collected. It sits in the genus Cyphocharax within the family Curimatidae — the toothless characins, a group placed alongside the other characiform "minor characins" (headstanders, hemiodontids and their relatives) that graze detritus and algae rather than hunting or browsing plants. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the governing authority for the valid name and combination; no recent generic transfer has moved this species out of Cyphocharax.
Cyphocharax magdalenae is notable within its family for its distribution: it is the only curimatid recorded as far north as Central America, reaching Panama and Costa Rica via the Coto River system, well outside the otherwise almost exclusively South American range of the family. GBIF and FishBase occurrence records place it from the Coto drainage on the Costa Rica-Panama border south and east through the Atrato, Sinú and Canalete basins of Colombia to the Magdalena-Cauca system and on to the Maracaibo basin of Venezuela.
Morphology
Cyphocharax magdalenae has the compact, fusiform, silver body typical of a curimatid: a moderately deep but streamlined profile built for holding position in current and moving in coordinated shoals rather than for sudden predatory bursts. FishBase records a maximum published size of 10.5 in standard length and a maximum recorded weight of 290 g, which is large for a characin generally and substantial for a detritivorous "minor" species specifically — this is a fish that reaches nearly a foot in length, not a nano species.
Like other Curimatidae, the mouth is small, subterminal to inferior and effectively toothless, an adaptation for scraping and ingesting fine detritus and biofilm from sediment and submerged surfaces rather than for biting prey or plant material. Colouration is unremarkable silver overall, consistent with a fish that relies on shoaling numbers and open-water schooling behaviour rather than camouflage or display for its ecology.
Habitat
Across its range Cyphocharax magdalenae is a river and floodplain fish, recorded from the middle and lower Cauca River of Colombia, the wider Magdalena-Cauca floodplain, and the Atrato, Sinú, Canalete, Coto and Maracaibo basins. Field accounts describe it forming large shoals over sandy substrate in the middle reaches of rivers, and it is a dominant, ecologically important component of the Magdalena-Cauca floodplain fish community, where genetic and ecological survey work documents it making up roughly 30% of the lower floodplain's fish population by numbers — a striking figure that underscores how central this unglamorous grazer is to the basin's food web and nutrient cycling.
Water chemistry reported from wild habitat (a tributary population at Rio Los Lotes, Costa Rica) runs alkaline, around pH 8.2, with low or undetectable nitrates, indicating clean, well-oxygenated flowing water rather than still, tannin-stained blackwater. In its northernmost Central American range it is the sole curimatid present and has been recorded alongside cichlids (Andinoacara, Isthmoheros), Ctenolucius pike-characins, tetras and gobies, indicating a mixed lowland river community rather than a specialised or isolated niche.
Feeding
Cyphocharax magdalenae is a specialist detritivore, and a stomach-content study from the Ciénaga Grande de Santa Marta floodplain in Colombia quantifies just how specialised: sampled diets ran 88.1% detritus, 11.3% phytoplankton and 0.6% zooplankton. That composition is squarely consistent with the family's toothless, sediment-grazing feeding mode — this is a fish that processes fine organic material and algal film from the substrate and water column rather than pursuing live prey or browsing macrophytes.
Its sheer abundance in the Magdalena-Cauca floodplain (up to roughly 30% of the fish community) means this detritivory is not a minor ecological footnote; the species is described as playing a key role in nutrient and sediment transport and cycling within the floodplain system, processing organic material at a population scale that few showier characins match.
Mating
Published work on Colombian Cauca River populations describes Cyphocharax magdalenae as a short-distance migratory spawner: rather than the long, basin-scale spawning runs of the pacus and Prochilodus, it appears to make more localised movements timed to seasonal cues, spawning twice yearly. No external sexual dimorphism or courtship display has been documented for this species in the sources reviewed here, and no aquarium breeding accounts exist to describe behavioural detail — its reproductive biology is known almost entirely from field and genetic study of wild populations rather than from captive observation.
Breeding
Cyphocharax magdalenae is a broadcast (egg-scattering) spawner with no parental care and no nest-building: genetic and life-history research on the Cauca River population documents small, adhesive eggs (roughly 0.5 in), a twice-yearly spawning pattern tied to short-distance migration, and a generation time of about 2.6 years. This matches the general Curimatidae pattern of open-water or floodplain spawning without guarding behaviour, in contrast to the nest-defending true piranhas or the mass-migratory, farm-bred pacus and Prochilodus elsewhere in this atlas's characin coverage.
There are no documented aquarium-breeding accounts for this species. It is not established in the hobby, and nothing in the available sources suggests it has been bred in captivity; its reproduction is understood entirely through field study of wild Magdalena-Cauca and Central American populations.
In the aquarium
Cyphocharax magdalenae is essentially absent from the aquarium trade — the only trade-adjacent account located is a single hobbyist forum thread describing wild-collected specimens, not an established or commercially bred fish. Anyone who does encounter it should plan around its real adult size (up to 10.5 in SL) and shoaling habit: this is not a nano community fish, and a single specimen in a small tank would be both undersized housing and behaviourally isolated, since wild populations form large shoals over open, sandy river reaches.
Water should follow the alkaline, well-oxygenated, flowing conditions reported from its native rivers (around pH 8.2, low nitrates) rather than the soft acidic blackwater often assumed for South American characins by default; strong filtration and good water movement would better match its river-grazing ecology. As a detritivore, a diet built around sinking algae wafers, spirulina and vegetable-based foods with limited protein would suit it far better than a typical meaty characin diet. Given how little trade or captive-care history exists for this species, anyone acquiring it should treat published care information as provisional and prioritise water-quality stability over experimentation.
Conservation
The IUCN Red List assesses Cyphocharax magdalenae as Least Concern (2022 assessment), reflecting its wide distribution across multiple Central and South American drainages and its continued abundance — indeed dominance — in the Magdalena-Cauca floodplain fish community. It is not targeted by the aquarium trade at any meaningful scale and there is no evidence of population decline from collection pressure.
The more relevant long-term concerns for this species track the general pressures on the Magdalena-Cauca basin, one of Colombia's most heavily modified and populated river systems: damming, water-quality degradation, floodplain wetland loss and sedimentation change. Because C. magdalenae is such a numerically dominant detritivore in that floodplain, its population health is a reasonable proxy for the ecological condition of the basin's nutrient-cycling base, even though the species itself is not currently considered at risk.