Taxonomy & naming
Pseudomystus stenomus (Valenciennes in Cuvier & Valenciennes, 1840) is the valid name in the Catalog of Fishes, originally described in Bagrus or a related genus. The type locality is Java. The store listing as 'cf. stenomus' means the exact identity of the fish sold has not been established, which is sensible given that the genus contains several similar species in the region.
Morphology
Pseudomystus are small bagrid catfishes of South and Southeast Asia, with a short adipose fin, four pairs of barbels, a serrated spine at the front of the dorsal and pectoral fins, and a body marked with pale and dark bands or stripes in most species. FishBase gives this species a maximum of 4.5 in TL.
Habitat
FishBase gives its range as Thailand to Indonesia, and notes that it inhabits rivers and streams. The type locality is on Java.
Feeding
Bagrids of this genus are nocturnal carnivores and omnivores that take insects, crustaceans, worms and small fish. Species-level diet data are not recorded in the sources available to the atlas. In captivity they accept frozen foods, live worms and meaty sinking pellets.
Mating
Mating behaviour is not recorded in the sources available to the atlas.
Breeding
Captive breeding of this species is not recorded in the sources available to the atlas.
In the aquarium
Offer plenty of caves and dark retreats; the fish are shy by day and active after dark. Avoid keeping them with fish small enough to be swallowed. Handle with care because of the pectoral and dorsal spines. FishBase lists 68–79 °F, pH 6.0 to 8.0 and hardness of 4 to 25 dH.
Conservation
The IUCN Red List assessed it as Least Concern in 2019, meaning it is not considered at risk of extinction at present. Lowland forest streams in its range are being cleared and polluted.