どん底[donzoko] very bottom
井底[seitei] well bottom
海底[kaitei] bottom of the ocean
海底ケーブル[kaiteikeeburu] undersea cable
丸底[maruzoko] round-bottom

基底[kitei] base
靴底[kutsuzoko] shoe sole
黒底翳[kurosokohi] black cataract
根底[kontei] root
周知徹底[shuuchitettei] (something) known to all

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