Taxonomy & naming
Aspidoras belenos was described by the Brazilian ichthyologist Marcelo R. Britto in 1998, from a creek along the Primavera do Leste–Paranatinga road in the rio das Mortes basin — part of the larger rio Araguaia system — in Mato Grosso State, Brazil. The genus Aspidoras was erected by Rodolpho von Ihering in 1907; its name joins Greek aspís ('shield') to the '-doras' of Corydoras, the larger genus it most resembles. Aspidoras is distinguished from Corydoras principally by a paired (dual) cranial fontanelle, together with small eyes and a generally small body.
The species belongs to the subfamily Corydoradinae of the armoured-catfish family Callichthyidae. The 2024 revision of the Corydoradinae by Dias, Tencatt and colleagues split the unwieldy old genus Corydoras into several lineages but retained Aspidoras as a valid genus, so A. belenos remains Aspidoras belenos under current Catalog of Fishes usage. The 2022 generic revision by Tencatt, Britto and co-authors upheld it as a valid species among the eighteen they recognised.
Morphology
Aspidoras belenos is one of the smaller corydoradines, reaching only around 1 in in standard length. It has the compact, deep-bodied Aspidoras form: an armour of two longitudinal rows of overlapping bony plates, a hard helmeted head with characteristically small eyes, and three pairs of short barbels around a downturned, sifting mouth. A diagnostic detail of the species is the bifid (forked) serrations along the posterior edge of the pectoral-fin spine.
In life the body carries a bright iridescence — whitish-yellow with a green sheen — over the pale ground, the shine that earned it the name belenos. As in the genus generally, the dorsal, pectoral and adipose fins each bear a stiff leading spine, and females tend to be larger and rounder-bodied than males.
Habitat
Aspidoras belenos is native to the rio das Mortes drainage within the rio Araguaia basin, on the central Brazilian plateau in Mato Grosso. It inhabits small streams and creeks of the cerrado highlands, typically clear, shallow, flowing waters over sand and gravel. Habitat of this kind is warm and tropical, generally soft and slightly acidic to neutral.
Like other corydoradines, A. belenos is a facultative air-breather: it rises periodically to gulp atmospheric air, absorbing oxygen through a modified, vascularised hindgut — an adaptation that lets small callichthyids endure warm, shallow waters where dissolved oxygen can run low, including the seasonally shrinking pools of the dry-season plateau.
Feeding
As a small member of Aspidoras, A. belenos is a benthic micro-omnivore and detritivore. It works over the streambed, using its barbels and downturned mouth to sift sand and fine sediment for tiny invertebrates — insect larvae, microcrustaceans and worms — and for biofilm and organic detritus, passing cleaned material out through the gill openings. Its very small mouth confines it to small food items. In aquaria it accepts sinking micro-pellets and wafers, small frozen and live foods such as bloodworm and brine shrimp, and the fine particles its tankmates leave behind.
Mating
A species-specific courtship account has not been published for A. belenos, but it follows the corydoradine pattern common to Aspidoras. These are egg-laying shoalers without pair bonds; when a female ripens, an attendant male takes up the classic 'T-position,' his body at right angles to her head. The female clasps a few eggs at a time in a basket of her pelvic fins and presses them onto a cleaned surface — a leaf, stone or glass — repeating the act until the clutch of adhesive eggs is complete. The parents form no lasting pair and do not guard the site.
Breeding
Detailed captive-breeding records for A. belenos are scarce, but it should behave like other small Aspidoras egg-scatterers. Spawning is generally prompted by a cool, generous water change imitating the onset of the rains, with the group skewed toward more males than females. The sticky eggs are deposited in small batches on firm surfaces and receive no parental care — the adults will eat them — so the eggs or the parents are separated. Eggs hatch within a few days, and once their yolk is absorbed the fry take microworm, baby brine shrimp and powdered foods. Documented clutch sizes for this species are not established in the literature.
In the aquarium
A tiny, peaceable catfish, A. belenos is well suited to a quiet community of small fish for the keeper prepared to meet a few corydoradine basics. It is a shoaling species and should be kept in groups of six or more, when it is active and confident; kept alone it is shy and stressed. Because bottom area matters more than height, a modest footprint serves a group well.
Provide soft sand or very smooth, fine rounded gravel — sharp grit abrades and infects the barbels these fish feed with — and keep the bottom clean, well-oxygenated and gently flowing. Aim for warm, soft, slightly acidic to neutral water. Its small size makes it an excellent companion for small tetras, dwarf cichlids and other calm community fish, but never for anything large enough to bully or eat it. As with all corydoradines, move it with a container rather than a net to avoid snagging the fin spines, and transport it with care, since a stressed animal can release skin toxins that may endanger the group in the confined volume of a bag.
Conservation
Aspidoras belenos is assessed by the IUCN as Least Concern. It faces no specific, severe or imminent threat at present, but as an endemic of the rio das Mortes headwaters in Mato Grosso its clear cerrado streams lie within one of Brazil's most rapidly converting agricultural regions, exposed to land clearance, water abstraction, siltation and pollution. Continued degradation of these small upland waters would be the principal concern for a narrowly distributed plateau species of this kind.