Taxonomy & naming
The bearded cory was described by the French naval surgeon-naturalists Jean René Constant Quoy and Joseph Paul Gaimard in 1824, in the report of the voyage of the corvette Uranie, as Callichthys barbatus — material taken near Angra dos Reis on the Rio de Janeiro coast. It was soon shifted into Corydoras, and for the better part of two centuries the hobby knew it as Corydoras barbatus.
The genus Scleromystax was erected by Günther in 1864 for exactly these long-bodied, bristle-cheeked, strongly dimorphic coastal catfishes. After decades of being treated as a mere subgenus of Corydoras, Scleromystax was resurrected as a full genus in the 2000s on the strength of morphological and molecular evidence, and the recent large-scale revision of the Corydoradinae by Dias, Tencatt and colleagues (2024) keeps it standing. Eschmeyer's Catalog of Fishes and FishBase both now list the species as Scleromystax barbatus (Quoy & Gaimard, 1824), and that is the valid name. The genus is small — a handful of species including S. macropterus, S. prionotos and the much-traded S. kronei — all confined to the Atlantic coastal drainages of south-eastern Brazil, and all sharing the bearded males and the preference for cooler, faster water that sets them apart from true Corydoras. The hobby still files them among the 'corys,' and rightly so in spirit, but they are their own lineage. The name Scleromystax kronei is treated as a synonym of this species in Eschmeyer's Catalog of Fishes.
Morphology
This is the longest of the cory-type catfishes: FishBase gives a maximum of about 4 in standard length, and mature males in good condition look longer still because of their trailing fins. The body is the familiar callichthyid build — two overlapping rows of bony scutes down each flank, a hard helmeted head, three pairs of barbels around a downturned mouth — but stretched and made gaudy.
The sexes scarcely look like the same animal. A mature male is spectacular: the flanks and back are marbled black over a golden-tan ground, the belly is a creamy 'beer-head' white from chin to tail, and the dark, mask-like head is splashed with gold-leaf blotches and a broad golden stripe running from between the eyes to the snout tip. He also grows the feature that names the fish — dense bristles of odontodes along each cheek, the 'beard' — together with greatly elongated pectoral-fin spines and extended dorsal rays that give him an ungainly, impressive profile. Females are far plainer: a light tan body with large grey-to-black blotches that merge into a wavy banded pattern along the side, no facial bristles, and a smaller, rounder build. There is, as the old catfish writers liked to say, no such thing as a bearded lady.
Habitat
Scleromystax barbatus is endemic to the Atlantic coastal drainages of south-eastern Brazil, recorded from the State of Rio de Janeiro south to Santa Catarina. The type locality lies in the fast, clear rivers that empty into Guanabara Bay, around 23° south — well outside the tropics proper. This is the key to the fish: these are cool, well-oxygenated, often briskly flowing streams, and the water can drop below 59 °F in the cooler months.
That cool-water origin makes it a genuinely subtropical species rather than a tropical one. FishBase lists it as freshwater and demersal, in water of pH about 6.0–8.0 and soft to moderately hard (dH ~2–25), at temperatures up to around 82 °F but happiest much cooler. In the aquarium it is unusual among corys in actively disliking warmth: kept at the 'standard' tropical 77–79 °F and above, especially in crowded or poorly oxygenated tanks, it becomes stressed and often fails to thrive, whereas a range of roughly 64–75 °F suits it well. Like other callichthyids it can gulp atmospheric air at the surface and absorb oxygen through its hindgut, a useful backup, but its real preference is for the high dissolved oxygen of cool running water.
Feeding
The bearded cory is a benthic omnivore that forages over the bottom in the manner of all corys, sifting sand and detritus through its barbels for small invertebrates, insect larvae and worms. In the aquarium it is undemanding at the table: it readily takes sinking tablets, granules and larger flakes, and relishes live or frozen bloodworm, whiteworm, grindal worm, Daphnia and Tubifex, which are also the foods used to bring a group into spawning condition. As with every cory, it should be fed a proper varied diet of its own and never left to scavenge leftovers or expected to 'clean' the tank — a well-conditioned, well-fed group is the precondition for everything else, including breeding.
Mating
Like other corydoradine catfishes, Scleromystax barbatus is an egg-scattering shoal spawner with the characteristic 'T-position' courtship and no lasting pair bond. When a female ripens, the group becomes restless and a male presses his body against her head at right angles. FishBase records the captive sequence in unusual detail: as sperm is released the female sinks to the bottom, rests on one pectoral fin while fanning with the other, and at that moment releases a few eggs into the basket formed by her pelvic fins, where they are apparently fertilised. She then carries the eggs to a cleaned surface and presses them into place before the cycle repeats. Because the species skews toward more males than females in active spawning groups, breeders typically keep a male-heavy ratio to encourage the competition that triggers it.
Breeding
Breeding the bearded cory is a rewarding step up from the easy beginner corys, and the difference is temperature. A conditioned group is best kept on the cooler side of its range, around 68–75 °F, and spawning is classically triggered by a large water change with markedly cooler water, mimicking the cold rain-fed spates of its coastal streams. The adhesive eggs are laid in small batches on plants, stones or the glass, a few at a time, until a clutch of several dozen accumulates. There is no parental care and the adults will eat the eggs, so the breeder removes either the eggs or the parents. Eggs hatch in a few days, and once the yolk sac is absorbed the fry take microworm, baby brine shrimp and powdered foods, growing into the gaudy adult colours only as the males mature. The species is well established in the hobby — Planet Catfish logs twenty independent breeding reports — but the cool-water requirement keeps it firmly a specialist's project rather than a commercial mass-bred fish.
In the aquarium
The bearded cory is a peaceful, gregarious community fish, but it is not a beginner's bronze cory and the most common way to kill it is to keep it too warm. Provide a cool, well-oxygenated, gently flowing tank: many keepers run it unheated in a temperate room and use a power filter as much for current as for filtration, aiming for the high-teens to low-twenties Celsius and never letting a stocked tank sit above about 77 °F for long. It is a shoaling species and wants to be in a group; give it the bottom space its size demands, on a substrate of soft sand or smooth rounded gravel, because sharp or chipped gravel abrades and infects the barbels it digs with. Border the open foraging area with driftwood and plants, with shade from bogwood, rockwork or floating cover to settle the fish. As a sizeable, calm catfish it makes an excellent companion for other cool-tolerant, peaceful community fish; avoid genuinely tropical-warm tanks and anything large enough to bully it. As with all corys, handle it with care — the stiff fin spines tangle in nets (a cup is safer), and a badly stressed fish can release skin toxins that, in the small volume of a bag or bucket, can poison the whole group.
Conservation
Scleromystax barbatus is assessed by the IUCN as Least Concern, last evaluated in 2018. It remains reasonably widespread across the south-eastern Brazilian coastal drainages and is not considered globally threatened. The caveats are regional rather than range-wide: the Atlantic Forest streams it inhabits are among the most heavily settled and developed in Brazil, ringing the Rio de Janeiro–Santos urban corridor, and they suffer from deforestation, pollution, water abstraction and damming. Those pressures fall hard on individual populations of a fish that specifically needs clean, cool, well-oxygenated running water. The aquarium trade adds little to the picture — the species is bred in captivity by hobbyists, even if not on a commercial scale — so the conservation story is about the integrity of its coastal-stream habitat rather than collection.