Taxonomy & naming
The mosaic cory was described in 1962 by the German aquarist and ichthyologist Gerhard Knaack and named for Harald Schultz (1909–1966), the German-Brazilian ethnologist, anthropologist and fish collector who studied indigenous peoples of South America and gathered many of its fishes. It was placed in the vast genus Corydoras Lacépède, 1803 (family Callichthyidae), where it remained for six decades.
In 2024 the large phylogeny-based revision of the Corydoradinae by Dias, Tencatt and colleagues (Zoological Journal of the Linnean Society, zlae053) split Corydoras into several genera, and the mosaic cory is now carried by FishBase and the Catalog of Fishes as Brochis haraldschultzi. The placement is taxonomically apt: Brochis is the lineage of larger, long-snouted, many-finned corys, and haraldschultzi has long been recognised as a long-snouted species. Notably, its famous look-alike Corydoras sterbai went into a different genus in the same revision (Hoplisoma sterbai), so the two mimics are no longer even congeners. We keep the hobby-familiar 'Corydoras haraldschultzi' as the heading and note the current Brochis combination.
Morphology
This is a medium-sized cory reaching about 2.5 in in standard length, robustly built on the armoured plan of the subfamily, with two rows of bony scutes along each flank and a hard helmet-like head. Its defining feature is the long, somewhat pointed snout — the hallmark of the Brochis-type long-nosed corys — set with three pairs of barbels.
The pattern is the source of the name 'mosaic': a dense, fine reticulation of dark brown to black spots and short vermiculations over a pale golden to cream ground, covering the head, body and fins in an intricate net. This is where the celebrated confusion with Corydoras (now Hoplisoma) sterbai arises, since the two are similarly patterned and live side by side. The reliable distinction is on the head: haraldschultzi shows dark spots on a pale (gold) background, whereas sterbai shows the reverse — pale (gold) spots on a dark background — and haraldschultzi has the much longer, more pointed snout against sterbai's blunt, rounded face. As in all corys the dorsal, pectoral and adipose fins carry stiff spines, and females are larger and rounder-bodied than males.
Habitat
Corydoras haraldschultzi is distributed across central South America in Brazil and Bolivia, in the Tocantins–Araguaia and upper Madeira (Guaporé/Iténez) systems; it is associated especially with the Rio Araguaia and the upper Rio Guaporé. In parts of its range it lives syntopically — in the very same stretches — with its mimic Corydoras sterbai, the two sharing habitat and, through Müllerian-style mimicry, a similar warning-like appearance that benefits both.
It is a fish of warm, clear to lightly stained rivers and creeks over sand, where it forages along the bottom. FishBase gives a temperature range of about 75–82 °F — a touch warmer than many corys — with a pH from acidic to slightly alkaline (about 6.0–8.0) and soft to moderately hard water (dH around 2–25). Like all members of the subfamily it is a facultative air-breather, surfacing to gulp atmospheric air and absorb oxygen through a vascularised hindgut, which lets it tolerate warm, low-oxygen water.
Feeding
The mosaic cory is a benthic omnivore and detritivore, and its long snout is more than cosmetic: long-nosed corys are adapted to probe deeper into sand and crevices than the short-snouted species, and where it co-occurs with sterbai the difference in head and snout structure lets the two partition food resources and avoid direct competition. It works the substrate continuously, sifting out small invertebrates, insect larvae, worms, micro-crustaceans and organic detritus and venting cleaned sand through the gills. In the aquarium it takes sinking pellets and wafers, frozen and live bloodworm and brine shrimp, and small settled foods, and should always be offered proper sinking fare rather than left to scavenge.
Mating
Like all corys, the mosaic cory is an egg-laying shoaler without a pair bond, using the genus's well-known courtship. A ready female cleans a spawning site and the group becomes active; a male takes the characteristic 'T-position' at right angles to her head, and she appears to take his milt at the mouth, then carries the fertilised eggs in a basket formed by her clamped pelvic fins to the cleaned surface. In this species the eggs are comparatively large — about 0.5 in across — and are laid a few at a time, mainly on the undersides of broad leaves close together, the sequence repeating until the clutch is complete.
Breeding
The mosaic cory has been bred in aquaria, following the standard Corydoras pattern with a few species-specific notes. Spawning is typically triggered by a cool, large water change simulating the rainy season. The female drops the fairly large (~0.5 in) eggs into the pouch formed by her ventral fins, then attaches the sticky eggs to a previously cleaned site — characteristically the underside of fern or other broad leaves — placing them close together. The adults give no parental care and will eat the eggs, so a breeder removes either the eggs or the parents. Eggs hatch within a few days and the fry, once their yolk is absorbed, take microworm, baby brine shrimp and powdered foods. As a larger, slower-maturing long-nosed cory it is considered a moderately challenging rather than beginner's breeding project.
In the aquarium
The mosaic cory is a rewarding, peaceful aquarium fish, prized for its intricate pattern and its larger size, but it has clear needs. It is strongly social and must be kept in a group of at least six — more is better — in a tank with generous floor area to suit its active bottom-foraging; lone or paired fish become withdrawn.
Soft sand is especially important for this long-snouted species, both because the delicate snout and barbels are easily damaged by sharp or coarse substrate and because deep sand lets it feed as it is built to. Keep the water warm — it prefers the upper cory range, about 75–82 °F — clean, well-filtered and well-oxygenated, with gentle flow and regular partial changes, and a broadly soft, slightly acidic to neutral chemistry. It is utterly peaceful and suits a community of tetras, larger rasboras, peaceful dwarf cichlids and similar calm fish, ideally alongside a group of its own kind. A frequent point of confusion is buying it mixed in with Corydoras sterbai; check the head pattern (dark spots on gold = haraldschultzi; gold spots on dark = sterbai) and the snout length. As with all corys, net it with a cup to avoid snagging the fin spines, and transport carefully, since a stressed cory can release a skin toxin lethal in the small volume of a bag.
Conservation
Corydoras haraldschultzi is assessed by the IUCN Red List as Least Concern (assessed 2020). It is reasonably widespread across the Tocantins–Araguaia and upper Madeira drainages of Brazil and Bolivia, and is collected for the aquarium trade without evidence that this threatens wild populations. Like all fishes of central Brazil's river basins it faces the regional pressures of deforestation, agricultural expansion, damming and pollution — the Araguaia–Tocantins system in particular has seen significant hydroelectric development — but as a species it is currently judged to be in no danger. Its close ecological tie to the mimicry system it shares with Corydoras sterbai is a reminder that the conservation of such fishes is bound up with the integrity of whole river communities, not single species in isolation.