Taxonomy & naming
Amphilius brevis was described by the Belgian-British ichthyologist George Albert Boulenger in 1902. It belongs to the family Amphiliidae, the loach catfishes of Africa, and to the genus Amphilius, a group of small, elongate, rheophilic (current-loving) catfishes found across sub-Saharan African rivers. The Catalog of Fishes treats Amphilius brevis as the valid combination, and the genus itself has not undergone the kind of wholesale reshuffling seen in some other catfish families.
Data on the species is sparse outside of the standard taxonomic and distributional record — no dedicated common name is established in the hobby or literature, and it is generally referred to only by its scientific name.
Morphology
Like other Amphiliidae, Amphilius brevis has the classic loach-catfish body plan: an elongate, somewhat flattened form, a broad head, and paired fins positioned and shaped to help the fish hold station against strong current on rock and gravel substrate. The skin is completely scaleless and covered in a protective mucus layer, a feature shared with loaches and several other catfish families and one with direct consequences for aquarium medication (see "In the aquarium").
Adult size is small: FishBase gives a maximum length of 3.5 in total length. This is the real, confirmed adult size for the species — there is no indication in the available sources that it grows any larger, so keepers can plan for a genuinely small fish rather than assuming a size trap in this particular case. Unlike many other catfish families, Amphiliidae do not carry the stiff, serrated, locking pectoral and dorsal spines typical of groups such as Synodontis or the ictalurids, and no venom has been reported for the family.
Habitat
Amphilius brevis is native to the Congo River basin in the Democratic Republic of the Congo, recorded from the river's middle and upper reaches. It favours fast-moving rapids and turbulent, highly oxygenated stretches of river — the rheophilic habitat typical of the genus, where a flattened body and gripping fins let it stay put in current that would sweep a less specialised fish downstream.
Specific water chemistry data for this exact species is sparse, but general parameters reported for its Congo River habitat run around 77–81 °F with a pH of roughly 7.0–7.5 and moderate hardness (6–10 dH) — mild, mineral-modest tropical river water rather than either the very soft blackwater of some Amazonian systems or the hard alkaline water of the East African rift lakes.
Feeding
As a nocturnal benthic species, Amphilius brevis is best understood as an opportunistic micro-predator and omnivore, foraging the bottom for invertebrates, detritus and small prey items largely after dark — the general pattern for the genus and for Amphiliidae as a whole. Detailed dietary study specific to this species is not available.
In the aquarium, catfish of this build typically do well on sinking pellets and frozen foods such as bloodworm or small crustaceans, offered after lights-out so a shy, nocturnal fish is not out-competed by more active, light-loving tankmates.
Mating
No specific courtship or spawning behaviour has been documented for Amphilius brevis in the available sources. Data is sparse for this species, and it should not be assumed to follow any particular pattern without confirmation — this is not a species with an established reputation for open-water egg-scattering, cave-guarding, or any other named strategy in the literature reviewed.
Breeding
There is no confirmed record of Amphilius brevis being bred in the home aquarium, and the available sources do not document its reproductive biology in detail. Rather than assign a breeding mode by assumption, it is more honest to say that breeding behaviour for this species is effectively unknown or unreported — consistent with its status as a small, little-studied river catfish that is rarely if ever seen in the trade or in captive-breeding programs.
In the aquarium
Amphilius brevis is genuinely small — 3.5 in total length at maximum — so it does not need the oversized tank that many other catfish eventually demand, but it does need current: a strong flow and high, stable oxygenation to mimic the rapids it comes from, along with smooth rock and gravel to grip. As with any scaleless catfish, its naked, mucus-covered skin makes it more sensitive than scaled fish to medications and especially to copper-based treatments; dose conservatively, often at half the standard rate, and prefer non-copper treatments where possible.
It lacks the locking, serrated spines that make many catfish awkward to net, so handling risk is lower than in spined families, but as a nocturnal fish it will still appreciate rockwork and cover to retreat into during the day. This species is rarely available in the aquarium trade, and given the thin state of husbandry knowledge, it is best suited to an experienced keeper prepared to treat it as a research subject as much as a display fish.
Conservation
The IUCN Red List assesses Amphilius brevis as Least Concern, based on a 2009 assessment. The species is considered stable within its native range in the Congo River basin, and it is not currently subject to any documented major threat.
As with many small, range-restricted African river catfish, ongoing pressures on the Congo basin — including habitat degradation, sedimentation and water-quality changes from human activity — are the general long-term concerns for species in this guild, even where, as here, the formal assessment remains favourable.