Gibson, C., Juffe Bignoli, D., Parenti, L. & Kottelat, M.
This species is considered endemic to the Mae Khlong and Chao Phraya basins in Thailand. Records from the Mekong basin in Lao PDR and Cambodia currently are not considered correct. Surveys throughout the whole of its confirmed range have been carried out over the last 15 years, but the species was not recorded (Ng and Kottelat 2007).
This species has not been seen alive either in the wild, or in captivity for over three decades (last specimen was found in 1974). It may already be extinct. Causes of population decline have been overfishing for the international aquarium trade, habitat loss due to infrastructure developments, and probably deterioration in water quality, particularly from pollution caused by agro-chemicals. It is therefore listed as Critically Endangered (Possibly Extinct), with an assumed population of less than 50 mature individuals.
Further survey within Thailand is recommended, and records of the species from the Mekong basin should be further investigated.
Authentic and type specimens are known only from the Mae Khlong and Chao Phraya basins in Thailand. The species has been reported from the Mekong basin in Lao PDR and Cambodia, but no authentic specimens are known from these countries. This fish is considered endemic to Thailand, where it is now possibly extinct. Surveys throughout the whole of its range have been carried out for the past 15 years and have failed to find the species again (Ng and Kottelat 2007).
This species has not been seen alive either in the wild or in captivity, for over three decades; the last specimen was found in 1974. Repeated surveys over the past 15 years have failed to find the species. Population reduction is therefore estimated to be greater than 90% (Ng and Kottelat 2007).
This fish was popular in the international aquarium trade as "Balantiocheilos melanopterus" but all wild stocks exported from Thailand were in fact Balantiocheilos ambusticauda. After the decline and extirpation of B. ambusticauda from Thailand, the Balantiocheilos species exported from Thailand are in fact captive-bred B. melanopterus (Ng and Kottelat 2007).
Overfishing for the international aquarium trade severely depleted the populations of this species up until the 1980s, when it possibly became extinct in Thailand. Habitat degradation and loss of floodplains and mainstreams of the Chao Phraya and Mae Khlong basins due to changing infrastructure (dams, weirs and locks) are also significant threats to this species. This fish is suspected to be sensitive to deterioration in water quality, particularly from pollution caused by agro-chemicals, which are heavily used in Thailand.