Taxonomy & naming
Corydoras froehlichi was described in 2016 by Luiz Tencatt, Marcelo Britto and Carla Pavanelli, who recognised it as a distinct species among the spotted, short-snouted corys of southern Brazil. The specific name honours Dr. Otávio Froehlich (1958–2015) of the Universidade Federal de Mato Grosso do Sul, a Brazilian zoologist. As described it sat in Corydoras Lacépède, 1803, the vast genus of South American armoured catfishes in the family Callichthyidae.
That genus had become an unwieldy assemblage of well over 170 species and was shown by molecular work not to be a single natural lineage. The 2024 revision of the Corydoradinae by Dias, Tencatt and colleagues split it into several genera — among them the resurrected Hoplisoma — and under that scheme this fish becomes Hoplisoma froehlichi; corydorasworld.com and FishBase now list it under Hoplisoma. The combination is recent and not yet universal, and the hobby still says 'Corydoras froehlichi,' so we keep that heading while recording the new placement. The species was once associated in the trade with the Paraguay drainage of the wider region, but the described material and type locality are in the upper rio Uruguai basin of Rio Grande do Sul, Brazil.
Morphology
This is a small, short-snouted cory reaching about 2 in in standard length, with the deep, flat-bellied, helmet-headed build typical of the group. Like all members of the subfamily it is armoured rather than scaled: two longitudinal rows of overlapping bony plates run down each flank, and three pairs of sensory barbels fringe the downturned mouth. The dorsal, pectoral and adipose fins each bear a stiff leading spine.
The colour pattern is the diagnostic feature — a pale ground broken by dark spots and blotches scattered over the head and flank, the markings that distinguish it from its close relatives in the southern Brazilian highlands. As with most corys the females are larger and rounder-bodied than the males. The precise meristic and osteological characters that separate it from similar spotted species are set out in the 2016 description.
Habitat
Corydoras froehlichi is known from the upper rio Uruguai basin in Rio Grande do Sul, southern Brazil — a subtropical, relatively cool highland drainage rather than the warm Amazon lowlands most aquarium corys come from. It is a benthic fish of stream and small-river habitats, living over sand and fine substrate among submerged structure.
Because it has not been the subject of dedicated ecological study, published water data are limited; the upper Uruguai is a clear-to-tannin-stained, well-oxygenated system that runs cooler and more seasonal than equatorial South American waters. Aquarium-relevant ranges below are inferred from the genus and the subtropical setting rather than measured at the type locality, and should be read as approximate.
Feeding
Like its relatives, Froehlich's cory is a benthic omnivore and detritivore. It works soft substrate continuously, burying snout and barbels to taste out small invertebrates, insect larvae, worms and the organic film of detritus, and expelling cleaned sand through the gills. No diet study specific to this species has been published, but the foraging mode is the same across the spotted southern-Brazil corys: an opportunist of the substrate-cleaning guild, taking whatever small live and fallen food the shallows provide.
Mating
Corydoras are egg-laying shoalers with no pair bond and a distinctive, well-studied courtship that there is every reason to expect this species shares. When a female is ready she cleans a site; a male positions himself at right angles to her head in the classic 'T-position,' and the female clasps a few eggs in a basket formed by her pelvic fins, carrying them to the cleaned surface and pressing them into place. The sequence repeats a few eggs at a time. The mating behaviour of C. froehlichi itself has not been documented in detail.
Breeding
No aquarium-spawning account specific to Corydoras froehlichi has been published, and it is rarely if ever kept. By analogy with related short-snouted corys, breeding would be expected to follow the familiar pattern: adhesive eggs laid in small batches onto cleaned surfaces, a cool water change mimicking seasonal rain as a likely trigger, no parental care (adults may eat the eggs), and fry hatching within a few days to take microworm and baby brine shrimp. As a cool-water subtropical species it may need a genuine seasonal temperature drop to come into condition. All of this is inference; the specifics remain undocumented.
In the aquarium
Corydoras froehlichi is essentially a specialist's and collector's fish rather than a trade staple, and reliable husbandry notes are scarce. The general rules for the genus apply with confidence: keep it as a shoal of six or more, never alone or in pairs, over soft sand or very smooth fine gravel so the barbels are not eroded, with clean, well-oxygenated water and a gentle current. Given its cool subtropical origin it should not be kept tropical-hot; a setup on the cooler side of the cory range, with seasonal variation, suits it better than steady warmth. It is a peaceful, retiring bottom-dweller best matched with calm subtropical tankmates. As with all corys, the fin spines can catch in nets — use a cup — and a distressed fish can release skin toxins that may prove fatal in the confined volume of a bag, so transport with care.
Conservation
Corydoras froehlichi has not been assessed by the IUCN, so its Red List status is Not Evaluated. As a recently described, apparently narrow-range species restricted to part of the upper rio Uruguai basin, it is the kind of fish whose conservation needs are easy to overlook: small-range southern-Brazilian stream species can be sensitive to deforestation, agriculture, damming and pollution in their headwater catchments. Until its true distribution and population are better understood, its status is genuinely unknown.