Bagrichthys is a genus of bagrid catfish native to Southeast Asia, with the atlas's 7 species recorded from Indonesia, Thailand, Cambodia, Laos, Malaysia, Vietnam, and China. They inhabit lowland rivers, peat swamps, and slow-flowing blackwater habitats across the Mekong, Chao Phraya, and Sundaic river systems, and range from roughly 6.5 in up to 15.5 in. The genus is easy to recognize by its distinctive silhouette: an elongated, laterally compressed body and, in several species, a tall, lance-like dorsal-fin spine that gives the group its common name of lancer catfish — a feature unusual enough among Southeast Asian catfish that it's the genus's clearest field mark.
Bagrichthys hypselopterus, the blacklancer catfish, is the species most likely to be seen in the aquarium trade, prized by catfish keepers for its tall dorsal sail and slender, elegant build, though its adult size and nocturnal, secretive habits make it a fish for larger, well-furnished tanks rather than typical community setups. Most of the rest of the genus, including B. macropterus (longfin bagrid) and the less-documented B. majusculus and B. micranodus, are known mainly from ichthyological surveys rather than the hobby. The IUCN picture is mixed and somewhat data-poor for the genus — three species are Least Concern, but three more are Data Deficient — suggesting several Bagrichthys species simply haven't been assessed closely enough yet to know how they're faring.