Taxonomy & naming
This fish circulated in the hobby under the collector code C065 for some years before it was scientifically described. Luiz Tencatt and Marcelo Britto published the formal description in 2016 (Neotropical Ichthyology), naming it Corydoras eversi for material from an unnamed stream tributary to the rio Araguaia in Goiás, central Brazil. The species honours the German aquarist and Corydoras specialist Hans-Georg Evers.
Like the great majority of the roughly 170-plus nominal 'cory cats,' it was placed in Corydoras Lacépède, 1803 (family Callichthyidae). That genus, however, proved not to be a single natural lineage, and in 2024 Dias, Tencatt and colleagues published a large phylogeny-based revision splitting it into several genera — Brochis, Hoplisoma, Osteogaster, Gastrodermus and others. Under that scheme this species becomes Hoplisoma eversi. The combination is recent and not yet universal, and the trade still says 'Corydoras eversi,' so we keep that as the heading while noting the current placement in Hoplisoma.
Morphology
Corydoras eversi is a small, fairly deep-bodied cory reaching roughly 2 in in standard length, with females growing larger and noticeably rounder than males. Like all members of the subfamily it is armoured rather than scaled: two overlapping rows of bony plates (scutes) run along each flank, the head is a hard, blunt casque, and three pairs of short barbels fringe the downturned mouth used to sift the substrate.
The distinguishing feature, and the source of its trade names, is colour. The body is a pale fawn to greyish ground crossed by fine dark reticulation and spotting, but the head, nape and shoulder region carry a warm orange-to-coppery flush — the 'guarana' or 'soda-pop' wash. The dorsal fin is marked, and as in all corys the dorsal, pectoral and adipose fins bear stiff, mildly venomous leading spines that can jab a careless hand or snag in a net.
Habitat
The species is known from the upper rio Araguaia system in central Brazil, part of the larger Tocantins–Araguaia drainage, with the type locality an unnamed clearwater stream tributary in Goiás state. These are the small, shallow, often clear or lightly tea-stained streams of the Cerrado and forest-margin country of central Brazil, typically running over sand with leaf litter and submerged wood.
No formal field measurements of its water chemistry have been published, so aquarium guidance is extrapolated from the broader habitat: warm, soft to moderately hard water that is slightly acidic to near-neutral. As with other corys it favours quiet marginal water with a clean sandy bottom over which it can forage, and like its relatives it is capable of facultative air-breathing, darting to the surface to gulp air absorbed through a vascularised hindgut.
Feeding
Corydoras eversi is a benthic omnivore and detritivore that works the bottom continuously, burying its snout and barbels in sand to taste out small invertebrates, insect larvae, worms, crustaceans and the organic film of detritus, expelling cleaned sand through the gills as it goes. It is an opportunist rather than a specialist. In the aquarium it readily takes all prepared foods that reach the bottom — sinking tablets, granules and larger flakes — along with live or frozen bloodworm, white worm, grindal worm, Daphnia and Tubifex, the last group being especially useful for conditioning a group for spawning.
Mating
No spawning account specific to C. eversi has been published, but corys share a distinctive, well-studied courtship with no pair bond. When a female is ready she cleans a site — a leaf, a stone, the glass — and the group becomes active; a male positions himself at right angles to her head in the classic 'T-position,' and she appears to take his milt into her mouth. Sperm is then thought to pass rapidly through her gut to fertilise the few eggs she clasps in a basket formed by her pelvic fins, which she carries to the cleaned surface and presses into place. The sequence repeats, a few eggs at a time, until the clutch is laid across the chosen surfaces.
Breeding
There is no published breeding report for Corydoras eversi, and it remains relatively uncommon in the hobby, but it is expected to follow the standard Corydoradinae pattern. Spawning in related species is typically triggered by a cool, large water change mimicking the rainy season, dropping the temperature several degrees, with a group skewed toward more males than females. The adhesive eggs receive no parental care — in fact the adults will eat them — so breeders move either the eggs or the parents. Eggs of related species hatch in three to five days depending on temperature, and the fry take microworm, baby brine shrimp and powdered foods once the yolk sac is absorbed.
In the aquarium
C. eversi is an attractive but still fairly scarce cory, occasionally available as wild imports or limited tank-bred stock. Its care follows the genus template. It is a shoaling species and is genuinely stressed when kept alone or in pairs, so keep six or more; a group is comfortable in a tank of around 23.5 in with a generous open bottom area, since footprint matters more than height.
Substrate is not optional decoration: provide soft sand or very smooth, rounded fine gravel, because corys feed by sifting and sharp or coarse grit erodes and infects their barbels, leaving the stubby, blunted faces that are a classic sign of poor husbandry. Keep the bottom clean. Water should be warm — roughly 72–79 °F — well filtered and well oxygenated, with a gentle current and regular changes; a slightly acidic to near-neutral pH and soft to moderately hard water suit it. It is utterly peaceful and makes an ideal companion for tetras, small rasboras, dwarf cichlids and other calm community fish, never anything large enough to bully it. Two standard cautions apply: the fin spines can catch in nets, so a cup is safer, and a distressed cory can release a skin toxin that, in the confined volume of a bag, can kill the whole group, so transport them with care.
Conservation
Corydoras eversi has not been assessed by the IUCN, so it carries no Red List status. As a recently described species with a restricted known range in the upper Araguaia system, its true distribution and population size are poorly documented, which is precisely why a formal assessment would be premature. The general pressures on central Brazilian freshwaters — agricultural expansion across the Cerrado, deforestation, siltation and damming — all degrade the small clearwater streams it depends on, and a narrowly distributed headwater specialist is inherently more vulnerable to local habitat loss than a widespread generalist. For now its conservation status is simply unknown and honestly so.