Taxonomy & naming
Isbrueckerichthys saxicola was described by Jerep, Shibatta, Pereira and Oyakawa in 2006, in Zootaxa No. 1372 (page 55, with figures 1 and 3). The type locality is the ribeirão Jacutinga, a stream in the rio Tibagi basin near Londrina, Paraná State, Brazil, at approximately 23°14'30" S, 51°13'05" W. The Catalog of Fishes (Eschmeyer, CAS) recognises the species as valid, and no synonyms are listed.
The genus Isbrueckerichthys belongs to the subfamily Neoplecostominae, a group of small, often torrent-dwelling armoured catfishes concentrated in the coastal and upland drainages of southeastern Brazil. The generic name honours the Dutch ichthyologist Isaäc J. H. Isbrücker, a prominent student of the Loricariidae, combined with the Greek ichthys, 'fish'.
Morphology
Isbrueckerichthys saxicola reaches about 3.5 in standard length, making it a small loricariid. As a neoplecostomine, it has the body form typical of stream-adapted suckermouth catfishes: a depressed, armoured body and a ventral oral disc suited to clinging to and grazing rock surfaces in current. Detailed diagnostic characters are given in the original description (Jerep et al., 2006); a full morphological account beyond the recorded maximum size is not reproduced here. No data on live coloration in life are available in the consulted sources.
Habitat
The species is associated with the upper rio Paraná system, in the Paranapanema and Tibagi drainages of the La Plata basin, in Paraná State, Brazil. These are clear, fast-flowing upland streams. The type locality, ribeirão Jacutinga, lies in the rio Tibagi basin near Londrina. Beyond the river-system context, no specific published physical and chemical water data (temperature, pH, hardness) are available in the consulted sources for this species.
Feeding
No feeding study has been published for Isbrueckerichthys saxicola. By analogy with other small, rheophilic neoplecostomine loricariids, it is presumed to graze the biofilm — algae, diatoms, and associated micro-organisms and detritus — that coats stones in fast-flowing streams, using its ventral oral disc. This is inferred from its ecology and body form, not from a published dietary analysis.
Mating
No data on courtship or mating behaviour have been published for this species.
Breeding
No breeding report exists for Isbrueckerichthys saxicola, in the wild or in captivity. The species is not noted in the aquarium hobby.
In the aquarium
Isbrueckerichthys saxicola is not present in the aquarium trade and has no documented husbandry history. It is a small rheophilic mountain-stream fish of limited interest to hobbyists and of restricted, threatened distribution; there is no basis in the published record for keeping recommendations, and given its conservation status it is not an appropriate target for collection.
Conservation
Isbrueckerichthys saxicola is assessed as Critically Endangered — the highest category of extinction risk short of Extinct in the Wild — reflecting its very restricted distribution in a small number of upper rio Paraná headwater streams. Narrowly endemic, current-dependent stream fishes of this kind are highly vulnerable to the pressures that affect southeastern Brazilian upland drainages: deforestation and the resulting siltation, agricultural runoff, water abstraction, urban expansion around centres such as Londrina, and the alteration of flow regimes by impoundments. For a species whose entire known range is so limited, degradation of even a few tributaries could threaten its persistence, which is why it warrants protection of intact, free-flowing stream habitat. A specific assessment year is not available in the consulted sources.