Taxonomy & naming
Platynematichthys notatus was described by the Scottish naturalist Sir William Jardine in 1841, originally placed in the genus Pimelodus before being transferred to Platynematichthys — a genus erected to accommodate this single species. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) treats Platynematichthys notatus (Jardine, 1841) as the valid combination. GBIF records the taxonomic placement as Platynematichthys within the family Pimelodidae, the long-whiskered catfishes of South America, one of the most speciose catfish families on the continent.
The genus is monotypic: Platynematichthys notatus is the only species it contains, giving it a certain ichthyological distinction. Its synonymy traces through early Pimelodus placements, and older literature may refer to it under those combinations. The family Pimelodidae contains many commercially important and aquaristically challenging giants (Brachyplatystoma, Sorubim, Pseudoplatystoma), and Platynematichthys sits among them in terms of potential size and ecological role.
Morphology
The lince catfish is immediately recognisable by its unusually tall dorsal fin, which bears a long, flowing filamentous extension — a trait that distinguishes it at a glance from most other pimelodids in the trade. The body is robust and laterally compressed toward the rear, with the broad, flat head typical of the family and three pairs of long barbels: a maxillary pair that extends well past the operculum, and two shorter mandibular pairs. The ground colour is pale to silvery grey with darker lateral markings that give rise to the common name "striped catfish".
FishBase records a maximum standard length of 31.5 in for the species overall; Orinoco Basin individuals are documented at up to 39.5 in SL, while Amazon populations appear to plateau around 19.5–23.5 in SL. As with all Pimelodidae, the skin is entirely scaleless (naked), a trait with direct consequences for medication sensitivity. The dorsal and pectoral fins are armed with stiff, serrated, locking spines that can be locked into the erect position as a defence mechanism — and can inflict painful injuries on anyone handling the fish without care.
Habitat
Platynematichthys notatus is native to two of South America's great river systems: the Amazon Basin and the Orinoco Basin. These vast lowland drainages share broadly similar conditions in their main channels and large tributaries — warm, soft to moderately hard water, slightly acidic to near-neutral pH, and high turbidity in white-water rivers, or tannin-stained clarity in black-water tributaries. The species is recorded across multiple countries within these basins, including Brazil, Venezuela, Colombia, Peru, and Guyana.
As a large, active pimelodid, Platynematichthys notatus is primarily a main-channel and large-river fish, patrolling open water rather than hugging dense structure. It is thought to be at least partially migratory, as many large pimelodids in these systems undertake seasonal upstream movements tied to reproductive cycles and prey availability. The species is uncommon in still or heavily silted backwaters; deep, well-oxygenated river sections are its typical habitat.
Feeding
Platynematichthys notatus is a dedicated piscivore — a fish-eater that will consume any fish or large invertebrate it can fit into its capacious mouth. In the wild it is an active predator in the river channel, taking fish across a wide size range; at 31.5–39.5 in SL, few fish in its environment are safe. This feeding strategy must inform every choice an aquarist makes about tankmates: anything small enough to swallow will be eaten, and what counts as "small enough" grows rapidly as the fish matures.
In aquarium conditions, established individuals accept frozen tilapia fillets, frozen shrimp and prawns, earthworms, chopped squid, and high-quality carnivore pellets. Live fish should be avoided for biosecurity reasons; a well-conditioned lince catfish will transition to prepared and frozen meaty foods if weaned gradually. Like most large pimelodids it is most active after dark, and feeding is most productive in the evening or after lights-out.
Mating
No detailed observations of courtship behaviour in Platynematichthys notatus have been published for either wild populations or aquarium specimens. The species belongs to the Pimelodidae, a family in which reproduction is generally understood to be seasonal and linked to the flood cycle of the host rivers — rising water levels, increasing temperatures, and changes in photoperiod appear to trigger upstream migrations and spawning in related large pimelodids.
Given its large adult size and the logistical demands of housing a breeding pair or group, mating has not been documented in private aquaria. At commercial scale, related large pimelodids are induced to spawn with hormonal treatment (typically fish pituitary extract or GnRH analogue injection), and it is reasonable to assume any captive breeding of Platynematichthys notatus would follow the same protocol. External sexual dimorphism is not documented in the available literature.
Breeding
Platynematichthys notatus has not been bred in the home aquarium, and realistically cannot be: the fish must reach substantial adult size before sexual maturity, requires space on the scale of a public aquarium installation, and — as with other large pimelodids — almost certainly needs hormonal induction to spawn. Commercial hatcheries in Brazil and Colombia produce related pimelodid species for the food-fish trade using hormone-induced spawning, and any reproduction of the lince catfish would follow that model.
The eggs and larvae of large pimelodids are typically pelagic or semi-pelagic, broadcast into open water with no parental care. Precise data for this species are absent from the hobbyist and aquarium literature, and it would be misleading to characterise the breeding mode in detail beyond this framework. Aquarists should approach this fish purely as a display animal, not a breeding project.
In the aquarium
The lince catfish is rated rare on the ornamental market, and with good reason: almost no private aquarium can house it properly. A specimen approaching its adult size of 31.5–39.5 in SL requires a minimum tank in the range of 200 US gal (roughly 10 ft × 4 ft × 4 ft), and even that figure is a starting point rather than an ideal. Public aquaria and very large private installations are the realistic destination for adult fish; anyone purchasing a juvenile should have this infrastructure in place or committed before the fish arrives, not after it has grown.
Two biology-driven care requirements follow from the species' body plan. First, the skin is entirely scaleless, making Platynematichthys notatus meaningfully more sensitive to copper-based medications and many standard aquarium treatments than scaled fish — doses should be conservative (half-dose is often recommended for scaleless species) and any treatment monitored closely. Second, the locking, serrated pectoral and dorsal spines make netting the fish genuinely hazardous both for the animal and the keeper; always move this fish in a large, solid container rather than a net. Water conditions should replicate the warm, soft to moderately hard, near-neutral parameters of the Amazon and Orinoco: temperature 75–82 °F, pH around 6.5–7.5. Tankmates must be fish too large to swallow — at 31.5 in, that is a very short list.
Conservation
The IUCN Red List assessed Platynematichthys notatus as Least Concern in December 2020. The species is distributed across the broad Amazon and Orinoco drainages, two of the world's largest and most intact river systems, and it does not face the extreme range restriction or specialised habitat requirements that place many South American catfish at higher risk.
That said, the Amazon and Orinoco basins are not without pressure: deforestation and sedimentation alter water quality and flood-pulse dynamics on which large migratory pimelodids depend, and the food-fish trade in Brazil targets related large catfishes. Platynematichthys notatus is sufficiently uncommon in catches and in the ornamental trade that direct harvesting pressure appears low. The species' conservation position should be revisited if basin-wide habitat degradation accelerates in its core range.