Taxonomy & naming
Corydoras gryphus was described in 2014 by Luiz Tencatt, Marcelo Britto and Carla Pavanelli, in a paper in Neotropical Ichthyology presenting it as 'a new long-finned Corydoras from the lower rio Paraná basin, Brazil.' The specific name gryphus is Latin for griffon — the mythical lion-bodied, eagle-headed and -winged creature — chosen in allusion to the conspicuous wing-like elongation of the pectoral-fin spine and dorsal-fin rays in males. It was placed, as nearly all such species were, in the huge genus Corydoras Lacépède, 1803 (family Callichthyidae).
In 2024 the large phylogeny-based revision of the Corydoradinae by Dias, Tencatt and colleagues (Zoological Journal of the Linnean Society, zlae053) split Corydoras into several genera, and the species is now carried by FishBase and the Catalog of Fishes as Hoplisoma gryphus. Co-author Tencatt's involvement in both the original description and the revision lends weight to the placement in the Hoplisoma lineage. The hobby-familiar 'Corydoras gryphus' is retained here as the heading, with the current combination noted.
Morphology
This is a small cory, reaching only about 1.5 in in standard length, with the standard armoured build of the subfamily: two rows of overlapping bony scutes down each flank, a hard helmet-like head, and three pairs of barbels around the downturned mouth. The fin formula recorded in the description is two dorsal spines, eight branched dorsal rays, seven branched anal rays and twenty-three vertebrae.
The species' signature is its sexual dimorphism in the fins. In males the first and second branched dorsal-fin rays are conspicuously elongated, drawing out past the tip of the dorsal spine to roughly the length of the spine itself, with the pectoral-fin spine and first ray similarly extended into a wing-like flag — a striking feature shared with only a couple of other corys (C. longipinnis and C. tukano). The species is further diagnosed by a strongly reduced posterior laminar expansion of the second infraorbital bone, by four to six irregular black or brownish blotches along the midline of the flank, and by the mesethmoid being entirely hidden beneath a thick layer of skin. Females lack the elongated fins and are the plainer, rounder-bodied sex.
Habitat
Corydoras gryphus is known from the lower Río Paraná basin in Brazil, in the stretch just downstream of the Itaipu Dam near the Paraguayan border. This places it well to the south of the Amazonian heartland of the genus, in the subtropical Paraná system. As a small benthic cory it is a fish of the quieter margins — shallow, slow-flowing reaches over sand and soft substrate, with leaf litter and submerged cover.
FishBase characterises it simply as a freshwater, demersal, tropical/subtropical species and does not publish a measured temperature, pH or hardness envelope specific to it, so precise water parameters for the species are not well documented; the figures used by aquarists are extrapolated from related lower-Paraná corys. Like all members of the subfamily it is a facultative air-breather, gulping atmospheric air at the surface and absorbing oxygen through a vascularised hindgut, which buffers it against low-oxygen conditions in warm, still water.
Feeding
As a small Corydoras, gryphus is a benthic omnivore and detritivore. It forages over the bottom, sifting soft substrate through its barbels and mouth to extract small invertebrates, insect larvae, micro-crustaceans, worms and organic detritus, and venting cleaned sand through the gills. No detailed dietary study specific to this species has been published, and its feeding ecology is inferred from the well-studied habits of its close relatives. In aquaria it would be expected to take sinking pellets and wafers, frozen and live bloodworm and brine shrimp, and small settled foods, as other corys do.
Mating
Corydoras are egg-laying shoalers without a pair bond, and gryphus follows the genus's well-known courtship. A ready female cleans a spawning site and the group becomes active; a male adopts the characteristic 'T-position,' lying at right angles to the female's head, and she appears to take his milt at the mouth. The few eggs she carries in a basket formed by her clamped pelvic fins are fertilised and then pressed, sticky, onto the cleaned surface, the sequence repeating a few eggs at a time. The males' exaggerated, wing-like fins are presumed to play a role in courtship display, as elongated finnage does in other dimorphic fishes, though the behaviour of this particular species has not been formally studied.
Breeding
There is little published on captive reproduction of this uncommon species, and what can be said follows the standard Corydoras template. Spawning in the genus is generally triggered by a cool, large water change simulating the rainy season; adhesive eggs are laid in small batches and stuck to cleaned surfaces, the adults giving no parental care and readily eating the eggs, so a breeder removes either eggs or parents. Eggs hatch within a few days and the fry take microworm, baby brine shrimp and powdered foods once their yolk is absorbed. Because gryphus is rare in the trade and only recently described, reliable first-hand breeding accounts are scarce, and prospective breeders should treat the genus-level pattern as a starting point rather than a recipe.
In the aquarium
Corydoras gryphus is seldom seen in the hobby, but as a typical small cory its requirements are clear. It is a shoaling fish that needs the company of its own kind — six or more — to behave naturally and feel secure, and it should be given a tank with ample floor area rather than height. Soft sand or very smooth, rounded fine gravel is essential: the barbel-led sifting that defines cory feeding is wrecked by sharp or coarse substrate, which erodes and infects the barbels.
Water should be warm, clean, well-filtered and well-oxygenated, with gentle flow and regular partial changes; lacking species-specific data, keepers default to the soft, slightly acidic to neutral, moderately warm conditions suited to small South American corys. It is a peaceful community fish best kept with calm tankmates such as tetras, pencilfish and dwarf cichlids, and never with anything large enough to harass it. Standard cory care applies: net the fish with a cup to avoid snagging the fin spines, and transport carefully, as a stressed cory can release a skin toxin lethal in the confined volume of a bag. The males' long fins make a well-kept group particularly attractive.
Conservation
Corydoras gryphus is listed by the IUCN Red List as Data Deficient (assessed 2020) — meaning there is not yet enough information on its distribution, abundance and threats to judge its extinction risk. That is unsurprising for a species described only in 2014 and known from a limited area of the lower Río Paraná. The stretch where it occurs, immediately downstream of the Itaipu Dam, is a heavily modified river system, and large dams, altered flow regimes, agriculture and pollution are all recognised pressures on Paraná-basin fishes; whether and how they affect this particular cory has not been established. As with many newly described, narrowly known corys, the honest position is that its status is genuinely uncertain and warrants further field survey.