The exact origin of this phrase is unknown but it starts appearing in literary works as early as 1483 when Geoffrey Chaucer penned: "...a huge man, uncouth; a master of vessel and knew all the ports; not ride well; like a fish out of water as sat on his horse." The phrase meant then, as it still does today, that someone is in a situation that they are unsuited for or unfamiliar with. ( source )

This one is pretty straightforward. Old fish (not good to eat) smells fishy with bad odor caused by a chemical named trimethylamine which is released when fish begins to break down. ( source ) What it means in the figurative is that something seems suspicious or shady.

Sea fish actively drink seawater, freshwater fish don't actively drink even though they appear to. So the phrase comes out of the illusion of fish drinking copious amounts of water. The phrase appeared in 1640, read all about it here .  When we say someone drinks like a fish we mean they are a heavy alcohol drinker.