Somphong’s rasbora (Trigonostigma somphongsi) is a small, tropical minnow-like ciprinid fish native to the Mae Khlong basin of Thailand. It is one of four species in genus Trigonostigma. It is considered critically endangered by the IUCN Red List of Threatened Species, as well as placed on the world’s 100 most endangered species list, due mainly to habitat degradation and development for farmland in addition to pressure from fishing. Somphong’s rasbora is highly sensitive to vegetation loss; it lays its eggs at the base of aquatic plants in a spawning behavior unique to, and characteristic of members of this genus. This species experienced a >90% population decline and in fact was considered extirpated as it was not been seen in the wild for more than twenty years. More recently individuals occasionally show up among catches of other small fish shipped from Thailand to Europe for the aquarium trade indicating there are existing populations. The localities and size of these populations are unknown but considered to be declining and presumably very local. Breeding captive populations do exist, and if wild populations can be identified and their habitat restored and protected, it may be possible to support existing wild populations by reseeding them with captive stock.
(Vidthayanon 2011; Kottelat and Witte 1999)