anadromous fish (fish that migrates upstream, e.g. salmon)
屍山血河
heaps of bodies and streams of blood, fierce battle
百年河清
waiting for one hundred years for the waters of the Yellow River to clear, waiting in vain for an unlikely event, waiting for pigs to fly, When the sky falls, we shall catch larks
星河豚
starry toado (pufferfish, Arothron firmamentum)
河岸を変える
to try a new venue for eating, drinking, night amusement, etc.