Taxonomy & naming
Corydoras cochui was described in 1954 by George S. Myers and Stanford H. Weitzman in the Aquarium Journal, in a short paper titled 'Another new Corydoras from Brazil.' The type locality is the Rio Araguaia at Santa Maria Nova, in the state of Goiás (then spelled Goyaz), Brazil; the holotype is held at the California Academy of Sciences (CAS-SU 47656). The specific name honours Walter Cochu, who supplied the original material to the describing authors.
For seventy years the fish was known as Corydoras cochui, within the huge genus Corydoras Lacépède, 1803 (family Callichthyidae, subfamily Corydoradinae). Because that genus proved not to be a single natural group, the 2024 revision by Dias, Tencatt and colleagues (Zoological Journal of the Linnean Society, DOI 10.1093/zoolinnean/zlae053) split it into several genera, and under that scheme Cochu's cory becomes Hoplisoma cochui — a notable point, since although it is a dwarf in size, it was placed not with the small elegans/hastatus-type Gastrodermus species but in Hoplisoma, the large genus that absorbed the majority of the old 'long-finned'/saddle-snouted Corydoras. The new combination is recent and not yet universally adopted; the trade still says 'Corydoras cochui,' so we keep that as the display heading while noting the current name. The little fish has also been muddled in the hobby with the superficially similar C. habrosus, under which name images of cochui have sometimes been published.
Morphology
Cochu's cory is one of the smaller species in the group, reaching roughly 1 in standard length (around 1 in total), with a slender body and a rounded snout, though it keeps the broadly triangular, deep-bodied silhouette typical of the family. Like all corys it is armoured with two rows of overlapping bony scutes instead of scales, and carries short sensory barbels around a downturned mouth.
The base colour of the body and head is a light brown. The defining pattern is a series of four dark blotches along each flank — one below the dorsal fin, one between the dorsal and adipose fins, one below the adipose fin, and one on the caudal peduncle — together with a dark streak running back from below the dorsal-fin spine and ending in a dark spot on the upper edge of the caudal peduncle. The top of the head is dark, continuing below the eye and onto the upper, front part of the gill cover. The tail is crossed by about five narrow, irregular dark bands — the 'barredtail' of the common name — and there is a dark spot at the base of the anal fin, with scattered dark spotting on the dorsal and pectoral fin rays. Like other corys it bears stiff, mildly venomous spines in the dorsal and pectoral fins, capable of a sharp sting, so it should be handled carefully.
Habitat
Corydoras cochui is endemic to the upper Araguaia River basin in central Brazil, part of the greater Araguaia–Tocantins system; Eschmeyer's Catalog and FishBase both give the distribution as the upper Araguaia basin, with the type series from the Rio Araguaia at Santa Maria Nova, Goiás. Hobby references extend the recorded range across the Araguaia and lower Tocantins. These are warm tropical lowland waters, and like other small corys the species is associated with calmer, shallow stretches over soft substrate with cover from wood, roots and marginal vegetation.
Recorded aquarium-relevant parameters are warm and broadly neutral: temperatures of about 73–79 °F, pH roughly 6.0–7.2, and soft to moderately hard water (around 2–25 °dGH). Like all corys it is a facultative air-breather, rising periodically to gulp atmospheric oxygen at the surface and absorbing it through a modified, vascularised hindgut — an adaptation for warm, oxygen-poor water. Detailed field ecology for the species is sparse; much of what is described is inferred from its habitat type and close relatives rather than from dedicated study.
Feeding
Cochu's cory is a foraging benthic omnivore, like the rest of the group. In nature it sifts soft substrate and detritus through its barbels and mouth for small invertebrates, insect larvae, micro-crustaceans and organic matter, scaled to its small size. In the aquarium it readily accepts prepared sinking foods — tablets, granules and larger sinking flakes — and relishes live and frozen items such as bloodworm, white worm, grindal worm, Daphnia and Tubifex, which are also useful for conditioning a group for spawning. A varied diet keeps it in good condition; it should not be left to live on leftovers or treated as a tank cleaner, and food must be small enough and actually reach the bottom past quicker tankmates.
Mating
Corydoras are egg-laying shoalers with no pair bond and a stereotyped, well-studied courtship, and cochui follows the same pattern. When a female is in condition the group becomes active and a male takes up the classic 'T-position,' aligning at right angles to her head. The female clasps a small number of eggs in a basket formed by her pelvic fins, where they are fertilised, then swims to a cleaned surface — a leaf, wood, fine plants or the aquarium glass — and presses the sticky eggs into place. The sequence repeats, a few eggs at a time, until a clutch is distributed across the chosen sites; there is no pairing or territory, only the brief, repeated spawning embrace.
Breeding
Cochu's cory can be bred along the same lines as other corys, and there are documented hobbyist breeding reports, though it is not as routinely propagated as the commercial staples. Condition a group well on live and frozen foods, favour a ratio of two or more males per female, and when the females are full of eggs use a large, cool water change with increased oxygenation and flow to simulate the rainy season and trigger spawning. The adhesive eggs are laid on the glass, plants or spawning mops and receive no parental care — the adults will eat them — so the breeder removes either the eggs or the parents. After a few days' incubation the fry absorb their yolk sacs and take tiny foods such as microworm and Artemia nauplii. Clean, stable water and a thin sand base aid survival of the small fry. Because the species is uncommon, captive-bred stock is comparatively scarce.
In the aquarium
Cochu's cory is a fine fish for a small, peaceful community, with the usual cory requirements honoured. It is a shoaling species and should be kept in a group of at least six; small numbers leave it nervous and reclusive, while a proper group is confident and busy. Being a dwarf it does not need a big tank — a base footprint on the order of 23.5 in is comfortable for a small shoal — but it does need the right floor. A soft sand substrate is effectively mandatory: corys feed by sifting, and sharp or chipped gravel abrades and infects the barbels, producing the eroded, stubby faces that mark poor husbandry. Border the open feeding area with driftwood and plants, and provide shade from bogwood, rockwork or floating cover to settle the group.
Water should be warm (about 73–79 °F), clean and well-oxygenated, with gentle flow and regular partial changes; the species tolerates a broad, near-neutral pH and hardness range. Choose tankmates appropriate to its small size — small tetras, pencilfish, rasboras and other calm, non-predatory species — and avoid anything large enough to bully or eat it. The standard cory cautions apply: the fin spines catch in nets, so a cup is safer for moving them, and a badly stressed cory can release a skin toxin that, in the confined volume of a bag or bucket, can kill a whole group, so transport them with care.
Conservation
Corydoras cochui has not been assessed for the IUCN Red List; its conservation status is formally Not Evaluated, and there is no published global extinction-risk rating for it. That is a genuine gap rather than a clean bill of health: the species is a relatively narrow-range endemic of the upper Araguaia basin, a system under pressure from agricultural expansion, deforestation, damming and pollution across central Brazil. Without a dedicated assessment, population trends are unknown. Collection for the aquarium trade is modest given how uncommon the fish is, but its limited distribution means habitat change in the upper Araguaia, rather than the hobby, is the more relevant long-term concern.