Taxonomy & naming
Sterba's cory was described by Gerhard Knaack in 1962, in Senckenbergiana Biologica, from material taken in the Rio Guaporé of central Brazil — still the type locality (holotype SMF 5476). It was placed in Corydoras Lacépède, 1803, the vast genus of South American armoured catfishes in the family Callichthyidae, and as Corydoras sterbai it has been traded, bred and written about worldwide ever since.
That genus had become a taxonomic problem: well over 170 nominal species, and molecular work showed it was not a single natural lineage. In 2024 Dias, Tencatt and colleagues published a large revision of the Corydoradinae that broke Corydoras into several genera (among them Brochis, Hoplisoma, Gastrodermus and Osteogaster). Under that scheme Eschmeyer's Catalog of Fishes now lists the species as Hoplisoma sterbai (Knaack, 1962). The combination is recent and the hobby still overwhelmingly says 'Corydoras sterbai,' so we keep that as the heading while flagging the current name. Unlike the bronze cory, sterbai is a single, well-defined species rather than a complex — its strong, distinctive pattern leaves little room for confusion, though it is regularly mixed up at a glance with the similar Corydoras haraldschultzi, which carries the inverse pattern (dark spots on a pale head rather than pale spots on a dark head).
Morphology
This is a small, deep-bodied, stocky catfish reaching roughly 2.5–3 in in standard length, with females growing visibly larger and rounder than males. Like all corys it is armoured rather than scaled: two overlapping rows of bony plates (scutes) sheathe each flank and a hard helmet of bone covers the blunt head, while three pairs of barbels fringe the downturned, sucker-like mouth used to sift the substrate.
The pattern is the species' signature. The head and nape are dark, almost black, overlaid with a dense scatter of small round cream-to-white spots; behind the gill cover these coalesce into rows that read as pale longitudinal stripes running back along the dark body. The standout feature is colour in the fins: the leading pectoral-fin spines are a vivid orange to yellow-gold, a flash that is brightest in healthy adult fish and is one of the quickest ways to separate true sterbai from look-alikes. Dorsal, pectoral and adipose fins each bear a stiff, mildly venomous spine — a defence that can deliver a sharp jab and snag in a net. A widely sold albino form (pink-white body, red eyes) has been fixed by long-line farm breeding.
Habitat
Corydoras sterbai has a comparatively small natural range, centred on the Guaporé (Iténez) River and the wider Mamoré–Madeira drainage of the upper Amazon basin, straddling the border between Mato Grosso and Rondônia in central Brazil and the Beni lowlands of northern Bolivia. It is a fish of smaller rivers, tributaries, quiet backwaters and seasonally flooded forest pools, typically over soft sand and leaf litter among submerged wood and roots.
These are warm, shallow tropical waters. Reported parameters span roughly 75–82 °F, a pH band from acidic to neutral (about 6.0–7.6) and soft to moderately hard water. What sets sterbai apart from most of its relatives is heat tolerance: it is one of the very few corys that remains comfortable at the high end of that range, and it is content at temperatures that would stress a bronze or peppered cory. Like other callichthyids it is a facultative air-breather, periodically darting to the surface to gulp air and absorb oxygen through a vascularised hindgut — an adaptation for the warm, oxygen-poor pools it inhabits in the dry season.
Feeding
Sterba's cory is a benthic omnivore and detritivore. In the wild it works the bottom continuously, burying its snout and barbels in sand and litter to taste out small invertebrates, insect larvae, worms, micro-crustaceans, fallen seeds and the organic film of detritus, flushing cleaned sand back out through the gills. It is an opportunist rather than a specialist, and that broad diet is part of its hardiness. In the aquarium it is easy to feed, taking sinking pellets and tablets, frozen and live bloodworm, Daphnia, Tubifex and brine shrimp, and anything its tankmates let fall — but it should never be left to scavenge leftovers alone; a dedicated sinking ration keeps a group in condition.
Mating
Like all corys, sterbai is an egg-laying shoaler with no pair bond and the characteristic 'T-position' courtship. When a female ripens she cleans a spawning site — a leaf, a stone, a broad plant blade or the aquarium glass — and the group grows active. A male positions himself at right angles to her head, forming a T, and she appears to take his milt directly; sperm is thought to pass rapidly through her gut to fertilise the few eggs she cradles in a basket made by her clamped pelvic fins. She then carries that small clutch to the cleaned surface and presses the sticky eggs into place. The sequence repeats, a handful of eggs at a time, often with several males attending a single female, until dozens of eggs are distributed across the chosen surfaces.
Breeding
Sterba's cory is widely regarded as one of the easier corys to breed, and it is produced commercially in enormous numbers, so almost every fish in the trade is captive-raised rather than wild-caught. Spawning is typically triggered by conditioning a group on rich live and frozen foods and then performing a large, cooler water change that mimics the onset of the rainy season. A productive group skews toward more males than females. The adhesive eggs receive no parental care — indeed the adults will eat them — so breeders move either the eggs or the parents. Eggs hatch in about three to five days depending on temperature; once the yolk sac is absorbed the fry take microworm, baby brine shrimp and powdered foods, and they grow steadily. Sterbai fry are a touch slower and more delicate than bronze-cory fry but are well within reach of an attentive hobbyist.
In the aquarium
Sterba's cory is an excellent aquarium fish, hardy and good-natured, but it rewards a few specifics. First, it is a shoaling species and is genuinely stressed kept singly or in pairs — keep six or more and they reward you with constant, confident foraging. A group is comfortable in a tank of around 23.5 in / 20 US gal or more, where bottom area matters far more than height.
Second, substrate is functional, not decorative. Provide soft sand or very smooth, rounded fine gravel: corys feed by sifting, and sharp or coarse gravel erodes and infects the barbels, leaving the stubby, blunted faces that are a tell-tale sign of poor husbandry. Keep the bottom clean. Where sterbai differs usefully from most corys is temperature: it tolerates the warm end of the tropical range, which makes it one of the few corydoras suited to a discus tank, though it does not require such heat and does perfectly well around 75–79 °F. Water should be well-filtered and oxygenated, with gentle current and regular changes; it accepts a broad pH and hardness range. It is utterly peaceful and an ideal companion for tetras, rasboras, dwarf cichlids and other calm community fish. Two cautions apply to all corys: the fin spines can catch in nets (a cup is safer), and a badly distressed cory can release a skin toxin that, in the confined volume of a bag or bucket, may kill the whole group — so transport them with care.
Conservation
Corydoras sterbai is assessed by the IUCN as Least Concern. Although its natural range is narrower than that of widespread corys like the bronze, it is locally common within the Guaporé–Mamoré system, faces no major range-wide threats, and — crucially — the overwhelming majority of fish in trade are commercially captive-bred, so collection pressure on wild populations is slight. That said, the upper Madeira basin is under growing pressure from deforestation, agricultural run-off, gold-mining sediment and mercury, and hydroelectric damming, all of which degrade the shallow marginal and flooded-forest habitats it favours. As a species it is in no immediate danger, but its relatively localised distribution makes habitat protection in the Guaporé worth watching.