the fish's natural range reached from the lower Mekong in Vietnam (above the tidally influenced brackish water of the river's delta) all the way to the northern reaches of the river in the Yunnan province of China, spanning almost the entire 4,800 km (3,000 mi) length of the river.[5] Due to threats, this species no longer inhabits the majority of its original habitat; it is now believed to only exist in small, isolated populations in the middle Mekong region.Fish congregate during the beginning of the rainy season and migrate upstream to spawn