Taxonomy & naming
Corydoras tukano was described in 2003 by Marcelo R. Britto and Flávio C. T. Lima, in a paper in Neotropical Ichthyology, from the rio Tiquié in the upper rio Negro basin of Amazonas, Brazil. The species name honours the Tukano (Tucano) Indigenous peoples of the upper rio Negro region. In the aquarium literature the fish had previously gone by a string of provisional labels — 'Corydoras species Asher,' Corydoras cf. reynoldsi and C. aff. reynoldsi — reflecting its close resemblance to the three-blotched C. reynoldsi.
It was placed in Corydoras Lacépède, 1803 (family Callichthyidae). That genus was later shown to be non-monophyletic, and the 2024 revision by Dias, Tencatt and colleagues (DOI 10.1093/zoolinnean/zlae053) split it into several genera. Under that scheme C. tukano belongs to the resurrected genus Hoplisoma, and FishBase now lists it as Hoplisoma tukano, the current valid combination. The hobby still says 'Corydoras,' so we keep that heading while noting the change. The Catalog of Fishes treats the name as valid.
Morphology
This is a small, short-snouted cory, reaching about 1.5 in standard length, of the usual deep-bodied armoured build: two rows of overlapping bony plates down each flank meeting in a dorsal ridge, a hard helmet of a head, and short barbels around the down-turned mouth.
Its distinction is its colour pattern, among the boldest in the genus. On a pale ground sit three large dark blotches: the first a 'mask' across the head and eye, the second on the trunk under the dorsal fin, and the third further back at the level of the adipose fin. This three-blotch scheme is shared only with Corydoras reynoldsi and C. weitzmani, and the details of the markings separate tukano from those two. The dorsal, pectoral and adipose fins each carry the usual stiff defensive spine.
Habitat
Corydoras tukano is known only from the rio Tiquié and its tributaries, in the upper rio Negro basin near the Brazil–Colombia border — the Tiquié being a tributary of the rio Uaupés. This is classic black-water and clear-water country: soft, acidic, tea-stained water draining ancient, nutrient-poor sands, over beds of white sand and leaf litter among submerged wood and root tangles in shaded forest streams.
These waters are warm, very soft and notably acidic, often well below pH 7, and the water values given here reflect that black-water character. Like all corydoradines the species is a facultative air-breather, surfacing to gulp air and absorb oxygen through a vascularised hindgut, which suits the warm, oxygen-poor margins it favours.
Feeding
Corydoras tukano is a benthic omnivore and detritivore, working the sandy bottom of its forest streams to sift out small invertebrates, insect larvae, worms, micro-crustaceans and organic detritus, expelling cleaned sand through the gill openings. No diet study specific to the species has been published, but its feeding anatomy is that of the typical sand-sifting cory and there is no reason to expect it to differ from the opportunistic, omnivorous habit of the group. In the aquarium it takes small sinking foods — pellets, frozen bloodworm and brine shrimp — sifted from a clean sand bed.
Mating
No spawning of Corydoras tukano has been formally documented in the scientific literature; the account here is the standard corydoradine pattern, offered as the expected behaviour. These are egg-laying shoalers without a pair bond: a ready female cleans a site, a male assumes the classic 'T-position' at right angles to her head, and she clasps a few eggs in a basket formed by her pelvic fins before pressing them onto the cleaned surface. The cycle repeats a few eggs at a time until a clutch of sticky eggs is distributed across leaves, stones or wood.
Breeding
Corydoras tukano has been bred in captivity by dedicated cory keepers, though it is regarded as moderately challenging and demands soft, acidic, scrupulously clean water to come into condition. Spawning follows the genus pattern: adhesive eggs laid in small batches on firm surfaces, typically triggered by a cool, large water change mimicking the rainy season, with no parental care — the adults will eat the eggs, so breeders remove eggs or parents. Eggs hatch in a few days and the fry take microworm, baby brine shrimp and powdered foods once the yolk is absorbed. Because wild fish come from a single restricted drainage, captive breeding is especially valuable for taking pressure off the natural population.
In the aquarium
The tucano cory is a prized, fairly uncommon fish, and unlike the bombproof bronze and panda corys it asks for conditions that match its black-water home: soft, acidic, warm water (it does not appreciate hard, alkaline tap water) and a clean, fine sand substrate into which it can sift without damaging its barbels. Keep it as a shoal of six or more — it is a sociable species that is stressed when kept alone — in a well-filtered, well-oxygenated tank with gentle current and regular water changes. It is peaceful and suits a quiet community of small soft-water fish such as pencilfish, small tetras and dwarf cichlids. As with all corys, the fin spines can snag in nets, and a distressed fish can release a skin toxin that may kill the group in the confined volume of a bag, so transport with care.
Conservation
Corydoras tukano is assessed by the IUCN as Least Concern, in an evaluation dating to 2020. That status sits a little uneasily against a species known only from the rio Tiquié and its tributaries: a single-drainage range makes a fish inherently sensitive to localised disturbance, and the upper rio Negro, while remote and relatively intact, is exposed to deforestation, small-scale gold mining and the pressures of the ornamental-fish trade. The most useful safeguard for a narrow-range cory like this is captive breeding, which reduces reliance on wild collection.