Taxonomy & naming
Akysis recavus was described by Heok Hee Ng and Maurice Kottelat in 1998. It belongs to the family Akysidae, the stream catfishes, a group of small, scaleless Asian catfishes often called hillstream or stream catfishes for their attachment to flowing water. The genus Akysis is large and still actively revised, with many species distinguished on fine details of head shape, barbel length and body proportions rather than colour pattern.
As with much of the genus, Akysis recavus is a narrow-range species known mainly from taxonomic literature rather than the aquarium trade or broad ecological survey, and it has not accumulated any English common name in general use.
Morphology
Akysis recavus is a genuinely miniature catfish, reaching only about 1.5 in standard length. Like other members of the genus it has a scaleless, naked skin, a flattened head and barbels used to feel out food and current on the streambed. It carries the stiff, serrated, locking pectoral and dorsal spines typical of small stream catfishes — spines that catch in a net and can jab an unwary hand, so this fish is best scooped and moved in a container rather than netted.
Beyond the original description, detailed morphological data for this species is sparse; FishBase and the wider literature offer little beyond the diagnostic size and family-level traits shared with its congeners.
Habitat
The species is native to mainland Southeast Asia, recorded from the Chao Phraya River system in Thailand and from the Mekong basin in Laos. Like other Akysis it is a fish of flowing water — streams and river reaches with current, oxygenation and a bottom of gravel, sand or rock rather than still, silty water.
Specific water chemistry data (pH, hardness, exact temperature range) has not been published for this species specifically, but it shares its habitat type with well-studied congeners that need well-oxygenated, moving water rather than stagnant conditions.
Feeding
Akysis recavus is a nocturnal benthic micropredator. It forages the streambed chiefly after dark, taking small aquatic invertebrates such as crustaceans, worms and insect larvae, along with zooplankton picked from the current.
In the aquarium, congeners in the genus are known to be selective about dried foods and do best on small live or frozen fare — Artemia, Daphnia, bloodworm and glassworm — offered after the lights go out so this small, retiring fish is not out-competed by more active tankmates.
Mating
Almost nothing has been published on courtship or spawning behaviour in Akysis recavus specifically. In the related genus, natural spawning is associated with the rainy season and a corresponding drop in water temperature, which may trigger reproduction, but no detailed account of pairing or courtship exists for this species. Sexing individuals is reportedly difficult even for closely related, better-studied Akysis.
Breeding
Breeding of Akysis recavus in captivity is essentially undocumented. Aquarists working with the genus describe it as very difficult to spawn at home, with almost no reliable reports of successful captive breeding across Akysis as a whole. There is no confirmed parental-care behaviour on record for this species. Anyone keeping it should treat it as a wild-collected, non-commercially-bred fish and not expect to breed it without considerable experimentation.
In the aquarium
This is a genuinely small catfish — about 1.5 in standard length at maximum — so it does not fall into the classic "size trap" of catfish that outgrow their tank, but its needs are still specific. It wants strong water flow and high oxygenation, more akin to a hillstream setup than a typical still community tank; hobbyist reports for the genus recommend turnover on the order of four to five times tank volume per hour even in a modest 45×12 in footprint. Provide sand or fine gravel, smooth rock and driftwood, and keep the tank well filtered and scrupulously clean.
Because it is scaleless, Akysis recavus is medication-sensitive — dose copper-based treatments and many standard medications conservatively, as with loaches and other naked-skinned catfishes. It carries locking pectoral and dorsal spines that snag in nets, so move it in a cup or container instead. It is nocturnal and appreciates caves, wood and shaded cover for daytime hiding, emerging to feed once the lights are off. Given its tiny size and secretive habits, it suits a species-focused stream biotope more than a general community tank.
Conservation
The IUCN Red List has assessed Akysis recavus as Data Deficient, most recently on 16 December 2010, meaning there is not enough information on its population, range extent or trends to judge its extinction risk. This is a common status for small, narrow-range Southeast Asian stream fishes that receive little targeted survey effort.
As a species restricted to specific reaches of the Chao Phraya and Mekong systems, it would be vulnerable to the general pressures facing mainland Southeast Asian rivers — damming, sedimentation and water-quality decline — but no species-specific conservation assessment beyond Data Deficient currently exists.