Bala shark, Balantiocheilos melanopterus (*)
Balantiocheilos is a small genus of cyprinid fish. It includes two species, B. ambusticauda and B. melanopterus.[1] Distribution The range of B. ambusticauda is listed as including the lower and middle Mekong and Chao Phraya River drainages in mainland Southeast Asia; the original distribution of this species included the Chao Phraya River drainage from Bangkok upriver to the lower Nan River and in the Mekong from Vietnam and the Great Lake (Tonle Sap) to the lower Nam Ngum River.[1] B. melanopterus occurs in the Mekong and Chao Phraya River basins, Malay Peninsula, Sumatra, and Borneo.[2] Description Cyprinid fishes of the genus Balantiocheilos are easily distinguished from other members of the family by the presence of thick and fleshy lips, the lower lip bearing a large lobe that is deeply incised medially along its posterior edge and black along the distal margins of the dorsal, caudal, anal and pelvic fins. The posterior margin of the lower lip has often been described as forming a posteriorly opening pouch or pocket between the lip and the skin of the throat.[1] B. ambusticauda can be differentiated from B. melanopterus by a shorter snout. Also, in B. ambusticauda the rictus (junction of the premaxilla and maxilla at the corner of the mouth) has posteriorly direct grooves that are curved instead of straight. Finally, B. ambusticauda has narrower black margins on the pelvic and anal fins (on the distal third or less instead of the distal half or more in B. melanopterus).[1] B. ambusticauda also has some golden color as opposed to the silvery B. melanopterus. B. ambusticauda only reaches about 20 centimetres (8 in) TL as opposed to 35 cm (14 in) TL in B. melanopterus.[1] Conservation B. melanopterus is listed as an endangered species by the IUCN Red List.[3] It has become rare or extinct in many river basins of its native range.[2] In Danau Sentarum (Borneo), fishermen already reported in 1993 and 1995 that the populations have decreased dramatically after 1975, for no clear reason. Fishermen mentioned overfishing for the aquarium-fish trade or forest fires in 1975 and the resulting pollution as possible causes. The species is apparently extirpated in the Batang Hari basin (Sumatra) and it seems that all individuals of B. melanopterus exported from Indonesia and Thailand by the aquarium-fish trade are captive bred.[1] B. ambusticauda is possibly extinct due to the aquarium fish trade, but this is unsubstantiated.[1] References
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