Taxonomy & naming
Aspidoras carvalhoi was named by Han Nijssen and Isaäc Isbrücker in 1976, in their foundational review of the genus, from two specimens taken at the Açude Canabrava (Cana Brava reservoir) at Guaramiranga, Ceará State, Brazil. The genus Aspidoras Ihering, 1907 is a small, exclusively Brazilian group of armoured catfishes (family Callichthyidae, subfamily Corydoradinae) close to Corydoras but distinguished by skull features, notably the retention of two cranial fontanels.
The sweeping 2024 revision of the Corydoradinae by Dias, Tencatt and colleagues (DOI 10.1093/zoolinnean/zlae053) divided the overgrown genus Corydoras into several genera (Brochis, Hoplisoma, Gastrodermus, Osteogaster and more) but left Aspidoras standing as an independent lineage; this species therefore remains Aspidoras carvalhoi, and Catalog of Fishes (Eschmeyer, CAS) treats it as valid. It is, however, valid in a precarious sense: when Tencatt and co-authors revised the genus in 2021 they could not provide a new diagnosis or redescription for A. carvalhoi, and were forced to exclude it from their identification key, because the material is too damaged and the original description too sparse to recognise the species reliably.
Morphology
Aspidoras carvalhoi is a small catfish, the holotype measuring about 1 in in standard length, built on the standard corydoradine plan: a stocky, armoured body sheathed in two rows of overlapping bony scutes, three pairs of barbels around a small ventral mouth, and stiff spines leading the dorsal and pectoral fins. Like the rest of the genus it carries the diagnostic pair of cranial fontanels.
Its colour pattern is, frustratingly, almost a non-feature. The original describers reported the body as 'almost completely devoid of chromatophores,' with only a few scattered minute brown spots near the edges of the lateral scutes, and even built that near-absence of pattern into their key. Later workers suspect this is misleading: the two specimens had already sat in preservative for nearly thirty years before being examined, so the living colour pattern had very probably faded. With the holotype now in poor condition, no dependable morphological diagnosis separating A. carvalhoi from its congeners has been possible.
Habitat
The species is known only from its type locality, the Açude Canabrava at Guaramiranga, in the Serra de Baturité — a moist, relatively cool, forested upland that forms a green island (a 'brejo de altitude') amid the semi-arid caatinga of Ceará. The reservoir appears to be drained by the rio Aracoiaba (Aracoiaba river) system. This is a different and much drier corner of Brazil than the Amazonian range of many corydoradines, and the highland streams here are isolated refuges of more humid conditions.
No direct measurements of temperature, pH or hardness exist for the fish, and no further specimens have been recovered from the Aracoiaba basin since 1947. Any water parameters quoted for it are inferred from the soft, warm-temperate upland streams of the region rather than recorded for this species, and should be treated as approximate.
Feeding
Nothing specific is recorded about the diet of Aspidoras carvalhoi. On the model of its congeners and the wider Corydoradinae it is presumed to be a benthic micro-omnivore, working soft sediment and leaf litter with its barbels to take small invertebrates, insect larvae, microcrustaceans and detritus, and passing cleaned sand out through the gills. This is inference from the genus; the species has never been observed feeding.
Mating
There are no observations of courtship or spawning in Aspidoras carvalhoi. The genus follows the corydoradine reproductive pattern — egg-laying shoalers without pair bonds, in which a female cleans a site, males gather and fertilise, and a few adhesive eggs at a time are clasped in the pelvic fins and placed on the chosen surface. Whether this species behaves likewise is entirely unconfirmed, the fish being known only from two long-preserved specimens.
Breeding
No breeding data exist for this species: clutch size, spawning triggers, egg and fry development are all unknown. Small Aspidoras that have been spawned in captivity lay modest batches of adhesive eggs with no parental care, the fry hatching within a few days and taking micro-foods once free-swimming. Any such expectation for A. carvalhoi is borrowed from relatives, as the species is absent from the aquarium hobby and has no recorded captive history.
In the aquarium
Aspidoras carvalhoi is not kept by aquarists and has effectively no presence in the trade; what little is occasionally labelled with this name in the hobby cannot be verified against the species, given that even specialists cannot recognise it from preserved material. If genuine fish were ever collected, they would presumably need the standard small-Aspidoras care — a shoal of six or more, soft sand to spare the barbels, gentle clean flow, warm but not hot water, and small peaceable tankmates — but these are genus-level guidelines, not husbandry tested on this particular catfish.
Conservation
Aspidoras carvalhoi is listed by the IUCN Red List as Data Deficient (assessed in 2018), and that is the honest verdict: the species is known from a single locality and just two specimens collected nearly eighty years ago, and cannot at present be reliably distinguished from its relatives. There is simply not enough information to judge its risk of extinction, a conclusion the 2021 generic revision reached independently. Its highland-stream home in the Serra de Baturité is a small, isolated, humid enclave under pressure from agriculture and water management, the kind of habitat where a narrow-range endemic could be quietly at risk — but without rediscovery and a modern redescription, even that cannot be properly evaluated.