河内[hanoi] Hanoi
運河[unga] canal
応急渡河[oukyuutoka] hasty crossing
黄河[kouga] Yellow river (in China)
河港[kakou] river port

河鹿[kajika] kajika frog (Buergeria buergeri)
河床[kashou] riverbed
河水[kasui] river water
河川[kasen] rivers
河童[kappa] kappa (mythical water-dwelling creatures)

溯る[sakanoboru] to go back
溯及[sokyuu] tracing back
溯源[sogen] returning to the origin

溯航[sokou] going upstream
溯河魚[sakkagyo] anadromous fish (fish that migrates upstream, e.g. salmon)

天魚[amago] land-locked variety of red-spotted masu trout (Oncorhynchus masou ishikawae)
海鷂魚[ei] ray (fish)
斉魚[etsu] Japanese grenadier anchovy (Coilia nasus)
旗魚[kajiki] marlin
鶏魚[isagi] chicken grunt (species of fish, Parapristipoma trilineatum)

杜父魚[tofugyo] sculpin (any fish of family Cottidae, inc. the bullheads and the miller's-thumb)
堅魚[katsuo] skipjack tuna
魚網[gyomou] fishing net
魚屋[sakanaya] fish market
魚貝[gyokai] marine products