Taxonomy & naming
Corydoras albolineatus was described by the German ichthyologist Joachim Knaack in 2004, in a paper describing six new Corydoras species (Zoologische Abhandlungen, Dresden). The type locality is the north bank of the lower Río Paraguá in the Río Iténez system, Santa Cruz Department, southeastern Bolivia — the Iténez being the same river known as the Guaporé on the Brazilian side. The specific name combines Latin 'albus' (white) and 'linea' (line), for the white longitudinal stripe along each flank. In the aquarium trade it had already been circulating under the code C056.
The genus Corydoras Lacépède, 1803 had become unwieldy — over 170 species and not a single natural group on molecular evidence. The 2024 phylogenomic revision by Dias, Tencatt and colleagues split it into several genera, and under that scheme this species is placed in the resurrected genus Hoplisoma. The Catalog of Fishes now gives its current status as 'Valid as Hoplisoma albolineatum (Knaack 2004)' (the neuter ending agreeing with the genus). Because the hobby still overwhelmingly uses 'Corydoras albolineatus' / 'C056', we keep that as the heading while noting the current combination.
Morphology
This is a small, short-snouted cory. The largest officially recorded wild female measured only about 1.5 in standard length, with males a few millimetres smaller; in the aquarium females have reached around 2 in and males 2 in. As in all Corydoras it is armoured with two rows of overlapping bony scutes down each flank, meeting along the back, a hard helmet-like head and three pairs of barbels.
Knaack's diagnosis sets it apart by a suite of characters: a wide, white longitudinal band along the body, with numerous small brown spots scattered over the top of the head and snout, and all the fins clear of markings. The snout is short and rounded in profile (snout length fitting 6.3–8.0 times in standard length), the dorsal and pectoral fins carry I,7 rays, the anal and ventral fins I,5, and the body bears 20–22 plates in the upper lateral row and 19–20 in the lower. It can be confused with the deeper-bodied C. xinguensis. The dorsal, pectoral and adipose fins each have a stiff leading spine, and the pectoral spines can sting.
Habitat
Corydoras albolineatus lives in the upper Iténez (Guaporé) drainage of Bolivia and adjacent Brazil — part of the upper Río Madeira system and so, ultimately, the Amazon. In the upper Iténez it most often occupies riparian zones with sandy substrates and the edges of sandbanks, but it has also been collected in smaller streams and residual flood pools. It is a strongly social, aggregating fish: it forms shoals of up to several thousand individuals, and at the confluence of the ríos Paraguá and Iténez it occurs alongside the congener C. paragua.
Field measurements taken at several localities between 2001 and 2003 found notably warm, soft, very low-conductivity water: temperatures of about 84–90 °F, a pH of roughly 6.5–7.5, and conductivity of only 24–27 µS/cm. The species tolerates a broad band in captivity (about 72–90 °F). Like all Corydoradinae it is a facultative air-breather, rising to gulp surface air and taking up oxygen through its vascularised intestine.
Feeding
The white stripe cory is a benthic omnivore. It forages over sand and the margins of sandbanks, sifting the substrate with its barbels for small invertebrates, insect larvae, worms, micro-crustaceans and detritus, and expelling cleaned sand through the gills. In the aquarium it accepts sinking dried foods readily along with small live and frozen items such as bloodworm and Tubifex; a varied diet keeps it in good condition, and it should not be relied on to live on other fishes' leftovers.
Mating
No spawning account specific to C. albolineatus has been published, but the genus follows a consistent and well-studied pattern. Corys are egg-laying shoalers with no pair bond: a receptive female cleans a surface, a male takes the classic 'T-position' at right angles to her head, and a few sticky eggs at a time are clasped in a basket formed by her pelvic fins and pressed onto the cleaned site. Given that this species naturally gathers in very large aggregations, group spawning would be expected, though the details for this species remain undocumented.
Breeding
There is little published on captive breeding of this species, which is only occasionally available. By analogy with other small short-snouted corys it would be expected to be an adhesive-egg layer, spawning in the typical T-position after a cooler water change, scattering modest batches of sticky eggs across firm surfaces with no parental care, and producing fry that take micro-foods and baby brine shrimp after the yolk sac is absorbed. We present this as inference from close relatives rather than as a documented breeding record for C. albolineatus.
In the aquarium
An attractive but uncommon cory, available occasionally and worth seeking out by aquarists who like the smaller, sand-shoaling species. Keep it as a group — at least six, ideally more, since in nature it lives in huge aggregations and is genuinely happier in numbers — over soft sand, which both suits its short-snouted sifting habit and protects its barbels from the erosion and infection that sharp gravel causes. Provide some cover for security and a clean, open sand bed for foraging.
It comes from notably warm, soft, low-conductivity water, so it is comfortable at the upper end of the usual cory temperature range and appreciates soft, gently acidic-to-neutral conditions, though it tolerates a broad envelope. It is peaceful and suits a calm community of small, gentle tankmates. As with all corys, move them in a cup rather than a net (the fin spines tangle), and transport them carefully, since a stressed cory can release skin toxins that may harm the whole group in the small volume of a bag.
Conservation
Corydoras albolineatus (as Hoplisoma albolineatum) was assessed by the IUCN in 2020 as Least Concern. It occurs in great abundance — shoals of thousands have been recorded — across the upper Iténez/Guaporé drainage, and faces no identified species-specific threat. As with all fishes of the region it is exposed to broad pressures such as deforestation, agricultural run-off and habitat alteration in the upper Madeira basin, but as a numerous and reasonably widespread species it is not currently considered at risk.