Taxonomy & naming
Brochis deweyeri was described by Hermann Meinken in 1957 from aquarium-imported material supplied by Marcel Van de Weyer, the Antwerp fish importer and retailer for whom it is named — the epithet deweyeri honouring the man who provided the holotype. (The species is sometimes mis-cited to other authors; the describing author is Meinken, 1957, not Boulenger.) Its type locality is given only as British Guiana, today Guyana, with no precise site, a reflection of its origin in the ornamental trade rather than a documented collection.
The name then drifted into uncertainty. Nijssen & Isbrücker, having examined the types, regarded 'Corydoras griseus deweyeri' as identical with Corydoras griseus Holly, 1940, and the name was widely treated as a subspecies or synonym. In 2021 Steven Grant, writing in the Catfish Study Group Journal, re-examined the question and concluded that B. deweyeri is in fact a valid species belonging to Lineage 8 — distinct from C. griseus, which is a Lineage 9 fish (now Hoplisoma griseum). The 2024 phylogenomic revision by Dias, Tencatt and colleagues (Zoological Journal of the Linnean Society, zlae053) then assigned Lineage 8 to the resurrected genus Brochis, making the current combination Brochis deweyeri. The hobby still says 'Brochis deweyeri,' so we keep that heading while noting the placement.
This fish was long listed as Corydoras deweyeri; Eschmeyer's Catalog of Fishes places the species in Brochis, and the current combination Brochis deweyeri is followed here.
Morphology
Brochis deweyeri is an intermediate long-snouted cory with a comparatively deep body — the build that characterises its lineage, between the blunt short-snouts and the most elongate long-nosed species. Reported sizes are about 2 in for males and 2.2 in for females. The body carries the standard Corydoras armour of two overlapping rows of bony plates, a hard helmeted head, three pairs of barbels around the downturned mouth, and stiff leading spines in the dorsal and pectoral fins.
In colour it is a grey, finely marked fish — the resemblance to the grey C. griseus is precisely what kept it tangled with that species for so long. The meristic and proportional details Meinken used to separate it (counts of dorsal and ventral fin rays, body depth, interorbital width) were long argued to fall within the range of griseus, and it took a dedicated modern reassessment to re-establish the distinction. As across the genus, females grow larger and fuller-bodied than males.
Habitat
Because Brochis deweyeri entered science through the aquarium trade rather than a documented field collection, remarkably little is known of its natural habitat. The type locality is recorded only as British Guiana (Guyana), location unknown, placing it among the corys of the Guiana Shield rivers of north-eastern South America.
No specific wild water data exist for the species. By the standards of its relatives it would be expected in the quieter shallows of forest streams and rivers — over soft substrates with leaf litter and submerged wood — and in the soft, often acidic waters typical of the region. Aquarium guidance places it in warm water around 73–79 °F at a near-neutral, slightly acidic pH (about 6.5–7.2). Like all corys it is a facultative air-breather, surfacing to gulp air absorbed through a vascularised hindgut.
Feeding
Brochis deweyeri is a benthic omnivore that works the bottom for small invertebrates, worms, insect larvae and organic detritus, sifting the substrate with its barbels in the manner of the whole genus; its intermediate long snout lets it probe a little deeper into soft sediment than the short-snouted corys. In the aquarium it is undemanding, taking good-quality flake and sinking tablet foods for the staple diet, with sporadic feedings of frozen or live foods to keep it in condition. As always with corys, it should be given a varied, properly sinking diet rather than left to subsist on what tankmates leave behind.
Mating
No spawning of Brochis deweyeri has been documented, but it is expected to conform to the standard Corydoras pattern. These are egg-laying shoalers with no pair bond. A ready female cleans a site, the group becomes active, and a male assumes the 'T-position' at right angles to her head; she is thought to take his milt, which passes rapidly through her gut to fertilise the few eggs she holds in a basket of clasped pelvic fins. She presses those eggs onto a cleaned surface and the sequence repeats a few eggs at a time until the clutch is complete.
Breeding
There is no published breeding report for Brochis deweyeri, which has been an obscure and uncommon fish for most of its history. By analogy with its relatives, spawning would be expected to follow a cool, large water change that mimics the onset of the rainy season, with a group skewed to more males than females. The adhesive eggs would be laid in small batches across firm surfaces and given no parental care — corys of this lineage routinely eat their own eggs — so a breeder would remove either eggs or parents. Eggs of comparable corys hatch in about three to five days, after which the fry take microworm, baby brine shrimp and powdered foods. This is informed expectation rather than a record for the species.
In the aquarium
Brochis deweyeri is, like the rest of the genus, a peaceful shoaling fish best kept in a group of six or more rather than alone or in pairs. Substrate is the key requirement, and especially for a longer-snouted species: provide soft sand, or at most smooth rounded fine gravel, never sharp or chipped material, which erodes and infects the barbels and produces the blunted faces that betray poor husbandry. Frame an open feeding area with driftwood and plants, and give the fish shaded retreats.
Water should be warm (around 73–79 °F), soft and near-neutral to slightly acidic, well filtered and well oxygenated, with regular partial changes. It is an ideal companion for small, calm community fish such as tetras, rasboras and danios, or it can be kept in a species tank for breeding; it should never share a tank with anything large enough to bully it. The usual cory cautions apply — the fin spines snag in nets, so a cup is safer, and a badly stressed cory can release a skin toxin lethal in the small volume of a transport bag, so move them carefully. It remains a rarely seen fish in the trade, still listed under its old Corydoras name on many sources.
Conservation
Brochis deweyeri has not been assessed by the IUCN Red List and carries no formal conservation status — unsurprisingly, given that its very identity was unsettled until recently and its natural range in the Guianas is recorded only as 'British Guiana, location unknown.' Without a documented wild distribution it is impossible to gauge any threat to the species, and there is neither evidence of decline nor of security. The Guiana Shield rivers it presumably inhabits are, on the whole, among the less heavily impacted in South America. For this fish the most pressing need is basic field data: pinning down where it actually lives is the prerequisite for any meaningful conservation judgement.