Taxonomy & naming
The false bandit cory was described in 1930 by the Swedish zoologists Einar Lönnberg and Hialmar Rendahl, from material gathered in the upper Rio Negro by the expedition naturalist Douglas Melin — who is honoured in the species epithet. They placed it in Corydoras Lacépède, 1803, the huge genus of South American armoured catfishes (family Callichthyidae), and as Corydoras melini it has been imported and bred ever since.
That genus had swollen to well over 170 species and molecular work showed it was not a single natural group. In 2024 Dias, Tencatt and colleagues published a large revision (Zoological Journal of the Linnean Society) that split Corydoras into several genera — including Brochis, Hoplisoma, Gastrodermus and Osteogaster — and under that scheme the false bandit becomes Hoplisoma melini, placed in the lineage built around the type species Hoplisoma punctatum. Eschmeyer's Catalog of Fishes now lists the species under this combination. The change is recent and not yet universal, and aquarists still overwhelmingly say 'Corydoras melini,' so we keep that heading while noting the new name. The 'false' in the common name marks the long-standing confusion with the true bandit cory, C. metae, and with the very similar C. davidsandsi — the three are routinely muddled in shops.
Morphology
This is a small cory, reaching only about 1.5–2 in in standard length; females grow larger and visibly rounder and broader than males, especially when gravid. Like all corys it is armoured rather than scaled: two rows of overlapping bony plates (scutes) run down each flank, meeting in a ridge along the back, and the head is a hard, blunt helmet, fringed below by three pairs of sensory barbels.
The ground colour is a clean, pale silvery body carrying two dark markings that make the fish. The first is the 'mask': a dark band crosses the top of the head and runs through the eye, the bandit stripe of the common name. The second is an oblique black bar that begins at the dorsal fin and sweeps diagonally back and down along the body toward the tail; in C. melini this band splits into two above the caudal peduncle — a detail it shares only with the closely allied C. davidsandsi. The cleanest way to separate the two is colour: C. melini lacks the warm orange wash that C. davidsandsi shows between the head stripe and the dorsal bar. The dorsal and pectoral fins bear stiff, mildly venomous spines that can tangle in a net.
Habitat
Corydoras melini is a blackwater specialist of north-western South America, recorded from the upper Rio Negro and Caquetá drainages of Brazil and Colombia and from the Meta–Orinoco system — FishBase summarises the range as the 'upper Negro and Meta River basins.' The type locality is Iauaretê, at the confluence of the rios Papuri and Uaupés in the Rio Negro system; the species is also known from the rio Tiquié, the Río Orteguaza in the Caquetá basin and the Río Losada in the upper Guaviare/Orinoco watershed.
These are classic blackwater habitats: pristine, tea-stained tributaries and flooded forest, the water dark with dissolved tannins, soft and acidic, flowing over sand and leaf litter. Wild fish live alongside small characins, pencilfish and dwarf cichlids such as Apistogramma. The water is warm and very soft — broadly 68–79 °F, with a wild pH that runs notably acidic (down toward 4.0, and rarely above neutral) and very low mineral content. Like other corys it is a facultative air-breather, surfacing to gulp air and absorb oxygen through a modified, vascularised hindgut.
Feeding
The false bandit cory is a benthic omnivore. It forages over the bottom, burying its snout and barbels in sand and leaf litter to taste out small invertebrates, insect larvae, worms and organic detritus, expelling cleaned sand through the gills. It is an opportunist rather than a specialist. In the aquarium it readily takes good-quality sinking dried foods alongside small live and frozen fare — chironomid larvae (bloodworm) and Tubifex are particular favourites — but, as with all corys, it should never be left to scavenge only what its tankmates drop.
Mating
Corydoras are egg-laying shoalers with no pair bond and a distinctive, well-studied courtship. When a female is ready she cleans a site — a leaf, a stone, the aquarium 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. 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 site and presses into place. The sequence repeats, a few eggs at a time, until the clutch is distributed across the chosen surfaces.
Breeding
C. melini has been spawned in aquaria, though it is a more demanding subject than the hardy bronze cory and rewards soft, acidic, blackwater conditions. A group skewed to more males than females — roughly two males per female — does best. Spawning is typically triggered by a large (50–70%) water change carried out with cooler water, mimicking the rains. The adhesive eggs are pressed onto glass and plants and receive no parental care — the adults will eat them — so breeders move either the eggs or the parents. Eggs hatch in about three to four days, and the fry, after absorbing the yolk sac, take microworm and baby brine shrimp; soft, clean, well-oxygenated water suits them through grow-out.
In the aquarium
The false bandit cory is a handsome, peaceful aquarium fish, but it is a step up from beginner-proof species and does best for keepers who can give it soft, acidic, scrupulously clean water. As with all corys it is a shoaling species and is genuinely stressed alone or in twos — keep six or more, and they reward you with confident, busy activity along the bottom.
Substrate is not optional decoration. Provide soft sand or very smooth, rounded fine gravel: corys feed by sifting, and sharp or coarse gravel erodes and infects their barbels, leaving stubby, blunted faces — one of the commonest signs of poor husbandry. Keep the bottom clean, because they are always nosing in it. Water should be warm (about 68–79 °F), soft and on the acidic side, well-filtered and well-oxygenated, ideally tinted with tannins from leaf litter or wood to echo the blackwater home; this species is less forgiving of hard, alkaline or dirty water than the bronze cory. They are utterly peaceful and make ideal companions for tetras, pencilfish, dwarf cichlids and other calm soft-water community fish. Two cautions worth knowing: the fin spines can catch in nets (a cup is safer), and a distressed cory can release a skin toxin that, in the confined volume of a bag or bucket, can kill the whole group — so transport them with care.
Conservation
Corydoras melini is assessed by the IUCN as Least Concern. It is reasonably widespread across the upper Rio Negro, Caquetá and Meta–Orinoco drainages, and faces no known species-wide threat. That status does not exempt it from the broad pressures on north-western Amazonian and Orinoco freshwaters — deforestation, mining sediment, agricultural run-off and pollution all degrade the soft, clear blackwater habitats it depends on, and as a blackwater specialist it is less buffered against water-chemistry change than a generalist like the bronze cory. The other live issues are taxonomic: its persistent confusion with C. metae and C. davidsandsi means trade and range figures should be read with some caution, and its recent move into Hoplisoma is still settling into general use.