Known from the Mekong basin (Ref. 43281). Occurs in the Khone Falls in the Mekong basin (Ref. 37772) and Ban Hang Khone at Don Khone, 3 km below the fall line of the great waterfalls of the Mekong basin at Lee Pee (Ref. 9497). Collected from Hatdokkeo, Tha Bo, Sai Fong, Sithan Tay, Hatsalao and Pathoun Phon of the Mekong basin (Ref. 4792). Among the most important species in the fisheries based on migrations in January-February and May-June (Ref. 9497). A strongly migratory fish species in the Khone area that does not go to Tam Ee Daeng, may be because it migrates upstream at a time when waters are low (April-early May) than when other species migrate. It goes only as far upstream as Boong Pba Jook (across from Hang Khone) before turning back and going up the channel to Hoo Sahong (Ref. 12369). Villagers catch them in the deep pools near the mouth of Hoo Sahong between Don Khone and Don Sadam (Ref. 12369). Fishers in Xayabury Province reported that it migrates downstream in October-November (Ref. 37770). Undertakes upstream migration during the wet season in May-June through Hoo Som Yai at the Great Fault Line on the Mekong River, Champassack Province (Ref. 37771). Museum: Mekong at Ban Hang Khone, just below Khone falls, CAS 94882 (Ref. 5515). Listed in Ref. 30857 as Pangasius cf. siamensis. P. macronema is an important fishery in the villages of Hang Sadam, Don Sahong, and Houa Sadam (Ref. 44002). Also Ref. 56905.