Taxonomy & naming
Corydoras multimaculatus was described by the Austrian ichthyologist Franz Steindachner in 1907, from a tributary of the Rio Prêto near Santa Rita de Cássia (Bahia), in the upper Rio Grande sub-basin of the Rio São Francisco system. The epithet is Latin for 'many-spotted', for its profusely spotted flanks. It belongs to the family Callichthyidae and subfamily Corydoradinae.
The huge genus Corydoras Lacépède, 1803 had long been recognised as an artificial assemblage, and in 2024 Dias, Tencatt and colleagues published a major revision dividing it among several genera (including Brochis, Gastrodermus, Osteogaster and Hoplisoma). Under that scheme the many-spotted cory becomes Hoplisoma multimaculatum — the combination now used by FishBase, Planet Catfish and the Catalog of Fishes (which lists the name as valid). The change is recent and the hobby still says 'Corydoras multimaculatus,' so we keep that heading while recording the current placement in Hoplisoma.
Morphology
This is a small, fairly stocky cory, reaching about 2 in in standard length, with a short rounded snout. Like all Corydoradinae it is armoured rather than scaled: two overlapping rows of bony plates run down each flank and meet along the back, the head forms a hard bony casque, and three pairs of barbels fringe the downturned mouth.
Its defining feature is the colour pattern its name records — a pale body covered in numerous small dark spots, spread densely and fairly evenly across the head, body and fins, giving the 'many-spotted' look. The dorsal, pectoral and adipose fins each carry the family's stiff leading spine. As in most corys, females grow larger and more full-bodied than males — best judged from above — while mature males tend to show more pointed fin tips.
Habitat
Corydoras multimaculatus is endemic to the Rio São Francisco basin of north-eastern Brazil, specifically the upper Rio Grande system and its Rio Prêto tributary in western Bahia. This makes it a biogeographic outlier among corys: the São Francisco is a large river isolated from the Amazon and the Paraná–Paraguay, draining the semi-arid interior of north-eastern Brazil, and it holds a distinctive endemic fish fauna of which this cory is part.
It is a bottom fish of streams and channels in this drainage, over sandy and gravelly beds with leaf litter and wood, in warm tropical water. Planet Catfish gives an aquarium temperature range of about 72–79 °F, consistent with the warm climate of the basin. As with the rest of the genus it is a facultative air-breather, gulping air at the surface and absorbing oxygen through a vascularised hindgut — useful in the warm, sometimes oxygen-poor and seasonally shrinking waters of the São Francisco interior. Detailed published water-chemistry data specific to the species are limited.
Feeding
No dedicated diet study has been published, but Corydoras multimaculatus is a typical benthic cory — an omnivore and detritivore that forages the bottom. It sifts sand and fine gravel with its barbels and downturned mouth, taking small invertebrates, insect larvae, micro-crustaceans, fallen organic matter and detritus, venting cleaned substrate through the gills. In the aquarium it readily accepts sinking tablets, granules and larger flake along with live or frozen bloodworm, white worm, grindal worm, Daphnia and Tubifex; varied feeding, including conditioning foods, keeps groups in good condition.
Mating
Spawning has not been documented for this species, but corys share a distinctive courtship it can be assumed to follow. They are egg-laying shoalers with no pair bond. A ripe female cleans a surface and the group becomes active; a male takes the 'T-position' at right angles to her head, and she appears to take his milt into her mouth. Sperm is thought to pass quickly through her gut to fertilise the few eggs she holds in a basket formed by her pelvic fins, which she presses onto the cleaned site. The cycle repeats a few eggs at a time until the clutch is laid.
Breeding
There is no published breeding report for Corydoras multimaculatus — Planet Catfish records none, and the species is only occasionally kept. By analogy with related Hoplisoma and Corydoras, spawning would be expected to follow the family pattern: adhesive eggs laid in small batches on leaves, wood, stone or the aquarium glass, often triggered by a cool, large water change mimicking the onset of the rains, with no parental care (adults may eat the eggs, so a breeder removes eggs or parents). Eggs of related corys hatch in three to five days and the fry take microworm, baby brine shrimp and powdered foods. None of this is confirmed for C. multimaculatus and is offered as informed inference rather than observation.
In the aquarium
Corydoras multimaculatus is an uncommon import — a small number of keepers maintain it — rather than a mass-produced community fish, so husbandry detail is modest, but its needs are the standard cory requirements. Keep it in a shoal of six or more, never singly, in a tank with generous bottom area. Substrate should be soft sand or, at most, smooth rounded fine gravel: corys feed by sifting, and sharp or chipped grit erodes and infects their barbels. Border the substrate with driftwood and plants, leaving open foraging space, and provide shade from rockwork, bogwood or floating plants. Water should be warm (about 72–79 °F), clean, well-oxygenated and well-filtered with gentle current and regular changes; the species tolerates a broad pH and hardness window. It is a peaceful, shoaling community fish best kept with calm tankmates — small tetras, rasboras and dwarf cichlids — and never with anything large enough to harass it.
Conservation
Corydoras multimaculatus has not been assessed by the IUCN Red List and carries no formal conservation status (Not Evaluated). As an endemic of the Rio São Francisco drainage it is of more conservation interest than its lack of assessment suggests: the São Francisco is a heavily modified river, with large dams, water diversion for irrigation, agriculture and pollution across a semi-arid basin under chronic water stress, and its endemic fishes face real pressures. The aquarium trade in this species is small and unlikely to be a significant factor. The honest position is that a basin-endemic of a stressed river system like this would merit formal evaluation, and its status presently remains unknown for want of an assessment and population data.