Taxonomy & naming
Kronichthys subteres was described by the Brazilian zoologist Alípio de Miranda Ribeiro in 1908, in the journal Kosmos (Rio de Janeiro), volume 5, number 2 (with figures 1 and 1a). The type locality is the rio Betari, in the rio Pardo / rio Iporanga area, within the rio Ribeira de Iguape system of Brazil. The Catalog of Fishes (Eschmeyer, CAS) treats the species as valid, and no synonyms are listed in the consulted sources.
The genus Kronichthys is placed in the subfamily Neoplecostominae, a group of small, generally rheophilic suckermouth catfishes of southeastern Brazil. The generic name honours Ricard (Ricardo) Krone, a naturalist associated with the Ribeira de Iguape region, combined with the Greek ichthys, 'fish'.
Morphology
Kronichthys subteres reaches about 4.5 in standard length. As a neoplecostomine loricariid it has the depressed, bony-plated body and ventral sucker-like mouth characteristic of stream-adapted armoured catfishes, an arrangement that lets the fish hold position on rock surfaces in current. Detailed meristic and morphometric diagnostic characters are given in the original description; they are not reproduced in full here, and no published account of live coloration is available in the consulted sources.
Habitat
The species occurs in the rio Ribeira de Iguape system (the Iguape drainage) of São Paulo State, southeastern Brazil. The type locality, the rio Betari near Iporanga, lies in the karstic, forested uplands of the Ribeira valley, where streams are typically clear and fast-flowing over rock. Specific published physical and chemical water data (temperature, pH, hardness) are not available in the consulted sources for this species.
Feeding
No dedicated feeding study has been published for Kronichthys subteres. Like other small rheophilic neoplecostomine loricariids, it is presumed to be a grazer of the biofilm — algae, diatoms, and the associated micro-organisms and fine detritus — that coats submerged rocks in running water, taken with its ventral oral disc. This is an inference from its ecology and body form rather than a documented diet.
Mating
No data on courtship or mating behaviour have been published for this species.
Breeding
No breeding report exists for Kronichthys subteres, in the wild or in captivity.
In the aquarium
Kronichthys subteres is essentially absent from the aquarium hobby and has no documented husbandry history. As a current-loving stream fish, it would in principle require cool, clean, well-oxygenated, fast-moving water with rocky surfaces for grazing, but no keeping experience has been published, and any such requirements are inferred from its natural habitat rather than reported by aquarists.
Conservation
The IUCN Red List assessed Kronichthys subteres as Least Concern, most recently in 2018, indicating that the species is not currently considered threatened across its range in the rio Ribeira de Iguape system. The Ribeira valley retains substantial forest cover, including protected areas, which helps maintain stream water quality. As with other southeastern Brazilian stream endemics, the longer-term outlook depends on continued protection of catchment forest and free-flowing water against deforestation, siltation, mining, and impoundment, but no significant population decline is documented at present.