Taxonomy & naming
The long-finned cory was described in 2007 by the German aquarist-ichthyologist Joachim Knaack, who named a number of southern South American corys, and placed in Corydoras Lacépède, 1803. The epithet longipinnis combines the Latin longus, 'long,' with pinna, 'fin' — a direct reference to the elongated dorsal and other fins, most pronounced in mature males. The Catalog of Fishes records the type locality in the Dulce River basin (Río Dulce / Salí system) of subtropical Argentina, an interior drainage of the country's central-northern provinces.
The genus Corydoras, with well over 170 species, had long been recognised as non-monophyletic. The 2024 phylogenetic revision by Dias, Tencatt and colleagues split it into several genera — Hoplisoma, Brochis, Gastrodermus, Osteogaster and others — and under that classification this species falls within Hoplisoma, the large lineage that includes the peppered cory and its southern relatives. The Catalog of Fishes and FishBase now list the valid combination as Hoplisoma longipinne, the epithet shifting to neuter agreement with the genus. Because the change is recent and aquarium usage still says 'Corydoras longipinnis,' we keep that heading while recording the current placement. The species also figures in modern revisionary work on the Corydoras paleatus (peppered cory) complex, with which it is closely allied.
Morphology
This is a fairly large, robust cory, reaching about 2.5 in in standard length, with the deep, stocky build characteristic of the peppered-cory group. It carries the family armour: two rows of overlapping bony scutes along each flank meeting in a dorsal ridge, a hard bony-plated head, and three pairs of barbels around the small ventral mouth.
The defining feature is in the fins. Mature males develop conspicuously elongated, filamentous fins — most strikingly an extended dorsal — which is both the basis of the name and a clear secondary sexual character; females are plainer-finned and, as usual in the genus, larger and rounder in the body. The colour is in the peppered-cory idiom: a pale to greyish ground overlaid with dark mottling and blotching. The dorsal and pectoral fins bear the standard stiff cory spines.
Habitat
Corydoras longipinnis is a fish of subtropical, southern South America. The Catalog of Fishes records its type locality in the Río Dulce basin of Argentina, and FishBase notes its occurrence in Argentina with possible extension into Brazil and Uruguay — placing it among the temperate-fringe corys of the continent's interior and southeast rather than the tropical Amazon.
That southern distribution matters for its requirements: like its relative the peppered cory, this is a cool-tolerant species suited to lower, more seasonal temperatures than tropical corys, comfortable roughly in the low-to-mid 20s °C and able to take cooler spells. It lives in the genus-typical way as a demersal fish of quieter, shallow waters over soft substrates. Like all callichthyids it is a facultative air-breather, gulping surface air and absorbing oxygen through a vascularised, modified hindgut to cope with warm, low-oxygen shallows.
Feeding
The long-finned cory is a benthic omnivore and detritivore. It forages over the bottom, working its snout and barbels through sand and litter to find small invertebrates, insect larvae, worms, micro-crustaceans and organic detritus, expelling sieved sand through the gills. FishBase places it at a trophic level near 3.0 — a small, opportunistic invertebrate-and-detritus feeder. In captivity it would take the usual cory fare of sinking pellets, frozen bloodworm and brine shrimp, alongside whatever settles from above.
Mating
As an egg-laying cory closely allied to the well-studied peppered cory, the long-finned cory is expected to follow the standard cory courtship. These are shoaling spawners without a pair bond. A ripe female cleans a spawning surface; a male — here conspicuous for his long fins — takes the classic 'T-position' at right angles to her head, and she appears to take milt directly, the sperm passing quickly through her gut to fertilise the few eggs cupped in her pelvic-fin basket. She carries that batch to the cleaned site and presses the adhesive eggs down, the sequence repeating until the spawning is complete. The male's elaborated fins are presumed to play a role in courtship display.
Breeding
No widely published step-by-step captive-breeding account exists for this species, but its close relationship to the peppered cory — one of the easiest of all egg-layers to spawn — is encouraging. In that group, reproduction is reliably triggered by a cool, large water change mimicking seasonal rains and a drop in temperature, to which this cool-water species should be well suited. The adhesive eggs are laid in small batches on firm surfaces, given no parental care (adults eat them if left), and hatch within days into fry that take microworm, baby brine shrimp and powdered foods. Specific clutch figures for this species are not documented, so none are asserted here.
In the aquarium
The long-finned cory is an uncommon but appealing aquarium fish, the males' trailing fins giving it a distinctive look, and its husbandry is that of the peppered-cory group. It is a shoaling species needing a group of six or more, and a soft sand substrate, which for corys is a welfare requirement rather than decoration — coarse gravel abrades and infects the barbels they feed with.
Importantly, as a subtropical, southern species it does not want tropical-hot water: cooler, well-oxygenated conditions in the low-to-mid 20s °C, with the seasonal temperature swing of a temperate climate, suit it better than a steady high tropical temperature, and it can be a candidate for an unheated or coolwater setup in a temperate room. Give it clean water, gentle filtration with some current, ample floor area and peaceful tankmates — other calm coolwater community fish rather than anything large or boisterous. The usual cory cautions hold: fin spines catch in nets (use a cup), and a severely stressed cory can release a skin toxin lethal in the confined volume of a bag, so move it with care.
Conservation
Corydoras longipinnis has not been assessed by the IUCN Red List; its conservation status is therefore formally unevaluated, and we record it as such rather than inferring safety. As a relatively recently described species with a southern, partly interior Argentine distribution centred on the Río Dulce basin, its true range and population are imperfectly known. The subtropical drainages of central-northern Argentina face real pressures — agricultural expansion, water abstraction, damming and pollution — and any narrowly ranged endemic there warrants attention; but in the absence of a formal assessment, no status should be assumed in either direction.