Taxonomy & naming
Corydoras boehlkei was described by Han Nijssen and Isaäc Isbrücker in 1982, in the Proceedings of the Academy of Natural Sciences of Philadelphia, from specimens taken in the Río Cuchime, about 20 miles upstream of the junction of the Río Caura and Río Erebato, in Bolívar State, Venezuela (roughly 5°45'N, 64°24'W) — still the type locality. The epithet honours the late James E. Böhlke, the Philadelphia ichthyologist who collected the type material.
The species was placed in Corydoras Lacépède, 1803 and remained there through every subsequent treatment until the genus was dismantled. In 2024 Dias, Tencatt and colleagues published a phylogenetic revision (Zoological Journal of the Linnean Society) that split Corydoras into several genera, and under that scheme this fish becomes Hoplisoma boehlkei — the placement confirmed by Eschmeyer's Catalog of Fishes. The aquarium world still uses 'Corydoras boehlkei', which we keep as the heading while recording the current combination. (Note: this species is from the Río Caura / Orinoco drainage of Venezuela, not the Río Meta of Colombia, with which it is occasionally confused.)
Morphology
This is one of the smallest corys, reaching only about 1 in in standard length — a genuine dwarf comparable to the well-known pygmy corys. It nonetheless shows the full Corydoradinae armature in miniature: two rows of overlapping bony scutes down each flank, a blunt helmeted head, three pairs of barbels around the small downturned mouth, and stiff spines in the dorsal and pectoral fins.
Its colour pattern of dark markings on a paler ground distinguishes it from the other small corys of the Orinoco tributaries. As a member of the Hoplisoma lineage it is a short-snouted form. Its diminutive size is the most immediately diagnostic thing about it and shapes both its ecology and its requirements in captivity.
Habitat
Corydoras boehlkei is known only from the Río Caura system, a major clear-water tributary on the right bank of the Orinoco in southern Venezuela, with the type material from the Río Cuchime. The Caura drains the Guiana Shield and runs clear and soft over sand and rock; the fish occupies shallow, slow-flowing margins and side-channels over sand and leaf litter, among submerged roots and vegetation.
These are warm, soft, acidic to near-neutral waters — temperatures around 72–79 °F and pH roughly 6.0–8.0. As in all the subfamily it is a facultative air-breather, gulping air at the surface and absorbing oxygen through a vascularised hindgut. Its known range is small, confined to one Orinoco tributary system, which is central to its conservation profile.
Feeding
No diet study has been published for this miniature, but it is a benthic micro-omnivore like its relatives, scaled to its size. It forages over sand and litter, using its barbels to find tiny invertebrates, micro-crustaceans, insect larvae, worms and organic detritus, taking in small mouthfuls of sediment and venting the cleaned grains through the gills. In the aquarium a fish this small needs correspondingly fine foods — micro-pellets, crushed flake, frozen cyclops and baby brine shrimp and small live foods grazed from the bottom.
Mating
Spawning has not been documented for Corydoras boehlkei, but the Corydoradinae share a uniform, well-studied courtship and dwarf species follow the same template. They are egg-laying shoalers without a pair bond: a ready female cleans a spawning surface, a male takes the 'T-position' at right angles to her head, she takes milt into her mouth, and the sperm passes through her gut to fertilise the small batch of eggs held in a pelvic-fin basket, which she presses onto the cleaned site — often plants or fine surfaces in the small dwarf species. The cycle repeats a few eggs at a time.
Breeding
There is no published aquarium-breeding account for this rarely kept dwarf, so reproductive detail follows the genus and the better-known pygmy corys. Such fishes lay small clutches of adhesive eggs on cleaned surfaces and fine-leaved plants, often triggered by a cool, large water change simulating the rainy season; they give no parental care and may eat the eggs, so breeders move the eggs or the parents. Eggs hatch in roughly three to five days, and the very small fry need infusoria-grade first foods before progressing to microworm and baby brine shrimp. Whether C. boehlkei has been bred in captivity is not on record.
In the aquarium
Corydoras boehlkei is rare in the trade and demands a little more care than a robust beginner's cory because of its tiny size. It is a shoaling species and should be kept in a group of six or more — ideally more, as dwarf corys are most confident in numbers — over soft sand, with leaf litter, fine wood and planting for cover. Water should be warm (about 72–79 °F), soft and slightly acidic to neutral, very clean and gently filtered, since a fish this small is intolerant of strong flow and poor water quality. Tankmates must be small and peaceful — nano fish such as small tetras, pencilfish, dwarf rasboras and the like — and nothing big enough to eat or bully it. As with all corys, move them in a cup rather than a net, and avoid crowding in transport.
Conservation
The IUCN Red List assesses this species (as Corydoras boehlkei) as Vulnerable, evaluated in 2017 under criteria B1ab(iii)+2ab(iii) — a listing driven by its small, restricted range and a continuing decline in the quality of its habitat. Known only from the Río Caura system, it has little geographic buffer: localised threats translate directly into range-wide risk. The Caura has so far been one of the less disturbed major Orinoco tributaries, but mining, deforestation and proposed hydroelectric development on Guiana Shield rivers are exactly the pressures the assessment flags. For a narrowly endemic dwarf like this, protection of the Caura's clear-water habitat is effectively protection of the species.