Taxonomy & naming
Corydoras cortesi was described by Donald M. Castro in 1987, in a study of the Corydoras of Colombia that named two new species (the Boletín Ecotrópica account). The type locality is the Río Arauca near the town of Arauca, in the Colombian llanos close to the Venezuelan frontier, within the Orinoco basin. The species belongs to the genus Corydoras Lacépède, 1803 (subfamily Corydoradinae, family Callichthyidae).
Its status has been muddled in the secondary literature: because it closely resembles Corydoras septentrionalis Gosline, 1940, of the Orinoco, several databases — FishBase among them — have at times treated cortesi as a junior synonym of that species. Eschmeyer's Catalog of Fishes, the naming authority, lists Corydoras cortesi as valid, and the 2024 Dias & Tencatt revision likewise recognises it. That revision split the oversized genus Corydoras into several genera (Brochis, Hoplisoma, Osteogaster, Gastrodermus and others), but cortesi sits in the long-snouted lineage retained as Corydoras in the strict sense — the group around the type species C. geoffroy — so its combination is unchanged. The epithet honours Abdón Cortés Lombana, a Colombian soil scientist, and not the conquistador the name superficially suggests.
Morphology
This is a small Corydoras, reported to roughly 2 in, females growing larger and fuller-bodied than males. It is one of the longer-snouted species, with a drawn-out head and a somewhat slimmer body than the stubby bronze and peppered corys — a profile that, together with its colour pattern, distinguishes it from the very similar C. simulatus, which has a shorter body. Like all callichthyids it is armoured rather than scaled, with two rows of overlapping bony plates down each flank and three pairs of barbels fringing the small, downturned mouth.
The ground colour is pale and silvery, overlaid with the dark reticulation and spotting typical of the long-snouted Orinoco corys; sexually mature males tend to carry more pointed fin tips than the rounder-finned females. As in the rest of the genus, the dorsal and pectoral fins each bear a stiff leading spine.
Habitat
Corydoras cortesi is known from the Río Arauca and associated waters of the Orinoco basin, on the Colombia–Venezuela border in the seasonally flooded llanos. Like other corys it is a bottom fish of soft substrates, foraging over sand and fine sediment in the shallow, slow margins of streams and rivers rather than open current.
These llanos waters are warm and run from soft and acidic to near-neutral, and the figures associated with the species sit in the usual Corydoras range: about 72–79 °F and a pH around 6.0–7.2. Like its relatives it is a facultative air-breather, periodically gulping atmospheric air at the surface and absorbing oxygen through a vascularised hindgut — useful in the warm, oxygen-poor backwaters and shrinking dry-season pools the llanos produce. Detailed field ecology for the species is sparse.
Feeding
No dedicated dietary study exists for C. cortesi, but it is a typical benthic omnivore–detritivore of its genus. It works soft substrate with its barbels and protrusible mouth, taking small invertebrates, insect larvae, worms, micro-crustaceans and the organic film of the streambed, sifting and expelling sand through the gills. In the aquarium it readily accepts all prepared foods that reach the bottom — tablets, granules and larger flakes — along with live or frozen bloodworm, white worm, grindal worm, Daphnia and Tubifex, the last especially useful for conditioning a group toward spawning. A varied diet, not a leftovers-only existence, keeps it in good health.
Mating
C. cortesi has no published spawning account, but corys are very uniform in their reproductive behaviour and it is expected to follow the genus pattern. These are egg-laying shoalers with no pair bond. A receptive female cleans a surface; a male takes the classic 'T-position' at right angles to her head, and sperm is thought to pass rapidly through her gut to fertilise the few eggs held in a basket formed by her pelvic fins. She then presses those eggs onto the cleaned site, and the sequence repeats a few eggs at a time until a clutch is spread across the chosen surfaces.
Breeding
There is no breeding report for C. cortesi, and it is not a commonly bred aquarium fish. By analogy with its relatives, spawning in the genus is usually triggered by a cool, large water change mimicking the rainy season, with groups skewed toward more males than females proving most productive. The adhesive eggs receive no parental care — the adults will eat them, so breeders remove either the eggs or the parents. Eggs hatch in a few days, and the fry, once the yolk sac is absorbed, take micro-foods such as baby brine shrimp and powdered fry feeds. All of this is inferred from close relatives; the species' own captive reproduction is undocumented.
In the aquarium
C. cortesi is an occasional import rather than a staple, but it makes an undemanding community fish with typical long-snouted-cory needs. It is a shoaling species and should be kept in a group of six or more; kept alone or in pairs it is stressed and skulking. Ideally provide soft sand — rounded fine gravel is an imperfect substitute, and sharp or dirty gravel erodes and infects the barbels of a fish that feeds by burrowing its snout — bordered with driftwood and plants and leaving an open foraging area, with shade from overhanging wood, rock or floating plants.
Water should be warm (about 72–79 °F), clean, well-filtered and well-oxygenated, with a gentle current and regular changes; the species tolerates a fairly broad pH and hardness range. It is entirely peaceful and suits a calm community of tetras, small characins, rasboras and dwarf cichlids, never anything large or aggressive. The usual cory cautions apply: the fin spines tangle in nets (a cup is safer), and a stressed cory can release a skin toxin that, in the small volume of a bag, can kill the whole group, so transport with care.
Conservation
Corydoras cortesi is listed by the IUCN Red List as Data Deficient (last assessed 2020) — there is too little information on its range, population and threats to assign a category. It is known from a restricted part of the Orinoco llanos, and although that region is not heavily industrialised, agricultural expansion, oil development and the seasonal hydrology of the llanos all bear on its habitat. Collection for the aquarium trade is light. Better field survey is needed before its status can be judged properly, which is precisely what the Data Deficient listing reflects.