Taxonomy & naming
Boeseman's cory was described in 1967 by Han Nijssen and Isaäc Isbrücker, the Amsterdam-based pair whose work on the Callichthyidae underpins much of what we know about the Guianan corydoradines. They named it for Marinus Boeseman (1916–2006), the Dutch ichthyologist and long-serving curator of fishes at the natural history museum in Leiden, whose South American collections supplied a great deal of the type material for the group. For most of its history the fish has been listed as Corydoras boesemani, within the enormous genus Corydoras Lacépède, 1803 of the armoured catfish family Callichthyidae.
That genus proved not to be a single natural lineage, and in 2024 Dias, Tencatt and colleagues published a large molecular revision (DOI 10.1093/zoolinnean/zlae053) that broke Corydoras into several genera, among them the resurrected Hoplisoma. Under that scheme this species becomes Hoplisoma boesemani, and FishBase and the specialist Corydoras World site have adopted the new combination. The change is recent and the aquarium trade still overwhelmingly says 'Corydoras boesemani,' so we keep that familiar heading while recording the current lineage name. The species sits among a knot of similar short-bodied Surinamese corys — surinamensis, breei and others — with which it can be confused without locality data.
Morphology
This is a small cory, reaching only about 1 in in standard length — distinctly smaller than the familiar bronze and peppered species of the hobby. The body is short and deep with the blunt, rounded snout typical of the 'short-nosed' corydoradines, and the head is the hard, helmeted shield of bone that gives the genus its name. As in all Corydoras (sensu lato) the flanks are armoured by two overlapping rows of bony plates rather than scales, and three pairs of barbels fringe the small, downturned mouth.
The colour is unshowy: a pale to brownish ground crossed by a darker, somewhat mottled patterning and the dark dorsal and shoulder markings common to the Guianan group. Sexes differ chiefly in build — females grow larger and noticeably fuller-bodied, which is most obvious viewed from above, while males stay slimmer with somewhat more pointed fins. The dorsal, pectoral and adipose fins each carry a stiff leading spine, the standard corydoradine defence.
Habitat
Corydoras boesemani is recorded from the coastal rivers of Suriname, on the Guiana Shield of north-eastern South America — a restricted range compared with the continent-spanning bronze cory. These are warm tropical lowland waters, and the species lives over soft bottoms in the quieter reaches where corydoradines characteristically feed.
The water it occupies is warm and broadly circumneutral: FishBase gives a temperature band of roughly 72–79 °F, a pH range from about 6.0 to 8.0 and soft to moderately hard water (around 2–25 °dH). Like other corydoradines it is a facultative air-breather, periodically darting to the surface to gulp air that it absorbs through a vascularised hindgut — an adaptation that lets it cope with the warm, oxygen-poor margins and seasonal pools of its lowland habitat.
Feeding
No detailed dietary study of this species has been published, but its anatomy and habits leave little doubt: like the rest of the group it is a benthic omnivore and detritivore. It works the bottom with its barbels, sifting sand and leaf litter for small invertebrates, insect larvae, micro-crustaceans and the organic film of detritus, taking in mouthfuls of substrate and expelling the cleaned grains through the gill openings. Its assigned trophic level (around 3.0) reflects that mixed invertebrate-and-detritus diet. In the aquarium it accepts the standard cory fare — sinking pellets and tablets, frozen bloodworm and brine shrimp, and small live foods worked into the substrate.
Mating
Spawning behaviour has not been documented specifically for C. boesemani, but Corydoras (in the broad sense) share a remarkably uniform reproductive pattern, so the general account almost certainly applies. These are egg-laying shoalers with no pair bond. A ready female cleans a spawning site, and a courting male takes up the classic 'T-position', aligning his body at right angles to her head; she appears to take milt directly, and a few adhesive eggs are clasped in a basket formed by her pelvic fins and then pressed onto the cleaned surface. The sequence repeats, a few eggs at a time, until the clutch is complete.
Breeding
There is no published or widely circulated captive-breeding record for this uncommon species, so any account is by analogy with its better-known relatives rather than direct observation — and we flag that honestly. In the corydoradines generally, spawning is often triggered by a cool, large water change mimicking the rainy season; the adhesive eggs are laid in small batches onto plants, wood or aquarium glass and receive no parental care, the adults readily eating them if the eggs or parents are not separated. Eggs typically hatch in three to five days, and the fry take microworm, baby brine shrimp and powdered foods once the yolk is absorbed. Whether C. boesemani follows this template exactly remains to be confirmed by aquarists who keep it.
In the aquarium
Boeseman's cory is a peaceful, small, shoaling catfish that turns up only occasionally in the trade, usually among mixed Surinamese imports. The usual corydoradine husbandry applies and matters more than its rarity. Keep it in a group of six or more — these are social fish that are visibly stressed kept singly or in pairs — over soft sand or very smooth fine gravel, because they feed by sifting and coarse or sharp substrate erodes and infects their barbels.
Given its small adult size, a modest, well-planted tank with a clean bottom, gentle current and good oxygenation suits it; aim for warm but not hot water (roughly 72–79 °F) and the soft, near-neutral chemistry of its home rivers, though it tolerates a fairly broad range. It is utterly peaceful and belongs with small, calm community fish — tetras, pencilfish, dwarf cichlids and the like — rather than anything boisterous. Two standard cautions hold: the fin spines tangle easily in a net, so a cup is safer, and a badly stressed cory can release a skin toxin that may prove fatal in the confined volume of a bag or bucket, so transport with care.
Conservation
The IUCN assessed Corydoras boesemani as Least Concern in 2021. Although its known range is fairly restricted, falling within the coastal rivers of Suriname, the assessment found no evidence of major threats to the species and no significant collection pressure — it is not a heavily traded aquarium fish. As with all the Guiana Shield freshwater fauna, the underlying risks are the broad ones of deforestation, mining, agricultural run-off and pollution degrading lowland streams, but as a species it is not currently considered to be in danger. Its restricted distribution does mean that local habitat damage would weigh more heavily on it than on the widespread species of the hobby, which is reason enough to keep an eye on the Surinamese drainages it depends on.