Taxonomy & naming
The hognose cory was described by the Ecuadorian ichthyologist Gustavo Orcés Villagómez in 1960 as Chaenothorax multiradiatus, from a tributary of the Río Lagartococha near Garza-Cocha in the upper Río Napo system, Napo Province, Ecuador — still the type locality. Chaenothorax was an early name for the large, many-rayed callichthyid catfishes, and the species was soon placed in Brochis Cope, 1872, the genus of big, deep-bodied 'brochis' that aquarists kept separate from the ordinary corys. The specific epithet — 'many-rayed' — flags the very feature that defines its place in the genus.
As with the rest of the brochis, the modern name shuffled twice. Britto's 2003 revision of the Corydoradinae sank Brochis into the giant genus Corydoras, so for two decades the fish was written Corydoras multiradiatus, the heading most FishBase, IUCN and trade material still uses. Then the 2024 phylogenomic revision by Dias, Tencatt and colleagues split the old Corydoras into several natural genera and resurrected Brochis, returning this species to it. The Catalog of Fishes now records the valid combination as Brochis multiradiata (Orcés V., 1960). The trade is slow to follow and 'Corydoras multiradiatus' or simply 'hognose brochis' will persist on tanks and lists for some time.
This fish was long listed as Brochis multiradiatus; Eschmeyer's Catalog of Fishes places the species in Brochis, and the current combination Brochis multiradiata is followed here.
Morphology
This is a large, bulky, heavily armoured catfish — among the biggest of all the cory-type fishes, reaching roughly 3.1–3.5 in (some references to about 3.9 in) — with the deep, high-backed body typical of the genus and the hard double row of bony scutes down each flank. Two features make it unmistakable. The first is the snout: it is conspicuously elongated and decurved into the 'hognose' that gives the fish its name, longer than in any other brochis, and is used to probe deep into soft substrate after food. The second is the dorsal fin, the genus diagnostic taken to its extreme — long-based and tall, carrying about 17–18 branched rays, against the ~15 of the giant B. britskii, the 10–12 of the emerald B. splendens, and the mere six or seven of an ordinary Corydoras.
The colour is more subdued than the brilliant emerald of B. splendens: a metallic green-to-bronze sheen over the flank, darker and more olive on the back, with the same pink-and-gold lower body. Three pairs of barbels fringe the long mouth, and the dorsal, pectoral and adipose fins each carry the stiff, mildly venomous locking spine of the family.
Habitat
B. multiradiata is a fish of the upper (western) Amazon basin, with a relatively restricted range across south-eastern Ecuador and northern Peru. The type locality lies in the upper Río Napo system in Ecuador; Peruvian records come from the Amazon-basin drainages including the Río Samiria and the Río Yavarí region. Specimens have been collected at modest elevations of a few hundred metres, in the kind of habitat the genus favours — smaller tributaries, backwaters, oxbows, flooded margins and still marginal pools over soft sand and mud with leaf litter and submerged wood.
These upper-Amazon waters are warm, soft and frequently tannin-stained. The species suits a temperature band of about 68–79 °F, a pH from acidic to neutral (roughly 6.0–7.5) and soft to moderately hard water. Like all callichthyids it is a facultative air-breather, surfacing to gulp air and absorb oxygen through a vascularised hindgut, which lets it cope with the warm, oxygen-poor pools and backwaters where the long snout earns its keep.
Feeding
The hognose cory is a benthic foraging omnivore, and its elongated snout is a feeding tool — it drives that long, hard nose deep into soft sand to root out prey other corys cannot reach, sifting the substrate with its barbels for invertebrates, insect larvae, worms, micro-crustaceans and the organic detritus and fallen plant matter of the shallows, then expelling the cleaned sand through the gills. In the aquarium it takes sinking dried foods — pellets, tablets and granules — along with frozen and live bloodworm, Tubifex and brine shrimp; a soft sand bed lets it forage naturally, and a varied diet keeps this big-bodied fish in good condition.
Mating
Like the rest of the brochis, B. multiradiata is an egg-laying shoaler that spawns in the standard corydoradine fashion, without a pair bond. A conditioned female brings the group into activity; a male takes the characteristic 'T-position' at right angles to her head, she appears to take his milt, and holding a small clutch of eggs in a basket formed by her clasped pelvic fins she carries them to a cleaned surface — plant leaves, wood or glass — and presses them into place. The cycle repeats a few eggs at a time until a scatter of large, adhesive eggs has been deposited.
Breeding
Aquarium breeding of B. multiradiata is essentially unreported in the literature, and the fish is rarely if ever bred in the hobby; almost every specimen in trade is wild-caught from the upper Amazon. There is no reason to think it departs from the corydoradine pattern — a mature group, high-protein conditioning and a large, cooler 'rainy-season' water change would be the levers to try, with the adhesive eggs moved away from the egg-eating adults to a separate container for rearing on microworm and baby brine shrimp once the yolk is absorbed. But because nobody has documented a reliable protocol, anyone keeping the species should treat spawning as an open question rather than a routine, and should source fish responsibly given that they are wild stock.
In the aquarium
The hognose cory is an impressive but demanding aquarium subject — a big, peaceful, wild-caught fish that needs more thought than a farmed bronze cory. It is gregarious and should be kept in a group of six or more; alone or in pairs it sulks. Its size and bulk call for room: a tank of around 35.4–47.2 in with a generous footprint suits a proper shoal, bottom area mattering far more than height.
Substrate is non-negotiable for this species above all, because the whole point of the long snout is to dig: provide deep, soft sand, which lets it forage naturally and protects the barbels and that elongated nose from the abrasion and infection that coarse or sharp gravel causes. Keep the water warm (about 72–79 °F), very clean, well-oxygenated and gently moving, with diligent water changes — wild-caught fish are less forgiving of neglected water than tank-bred corys — and lean toward soft, slightly acidic conditions. It is entirely peaceful and mixes well with tetras, pencilfish, larger rasboras, dwarf cichlids and other calm community fish. The usual corydoradine cautions hold: the locking fin spines snag in nets, so use a cup, and a badly stressed fish can release a skin toxin lethal in the closed volume of a transport bag, so move them carefully.
Conservation
Brochis multiradiata (assessed by the IUCN under the name Corydoras multiradiatus) is listed as Least Concern. The assessment notes no major range-wide threat, though its distribution in the upper Amazon of Ecuador and Peru is more restricted than that of the widespread emerald cory, and the population is supplied to the trade entirely by wild collection rather than captive breeding. That makes it more exposed in principle to local pressures — habitat degradation from deforestation, agriculture and pollution in its headwater drainages, and sustained collection from a narrower range — so while the species is currently secure, it warrants more careful attention than the farmed corys, and the case for developing a captive-breeding protocol is a real one.