Ambastaia is a genus of small, active loaches - the taxonomic home most aquarists know through one famous fish, the dwarf chain loach, Ambastaia sidthimunki. The genus sits within the wider clown-and-chain-loach lineage of family Botiidae, sharing that group's boldly patterned skin, barbeled snout, and habit of moving in loose shoals along river bottoms and rocky riffles. The atlas covers 2 species, 2.5–3 in as adults, native to river systems in Thailand, China, Laos, and Myanmar.
Both Ambastaia species are well-established aquarium fish and among the most recommended small loaches for community tanks - peaceful, actively schooling, and useful for picking off snails and leftover food, without the size or territorial edge of their larger Botia relatives. That popularity sits alongside real conservation concern: Ambastaia sidthimunki is assessed Endangered and Ambastaia nigrolineata Vulnerable, pressures tied to dam construction and habitat loss across their native Southeast Asian rivers, and one of the two species carries CARES conservation-priority status in the atlas.