Do Fish Pee?
 

ok. slow day at work. Just started thinking about fishes. We all know they poop, but do you think they pee? I'm thinking they use a type of osmosis to expel excess liquids out through their skin, but what do I know?

Short answer is yes.

They sure do.
http://www.infovisual.info/02/033_en.html

but what do they drink?

Saltwater species drink sea water to make up for the water they lose to the environment via osmosis.

Freshwater species gain large amounts of water through osmosis.

OK, I've caught tons of fish, and when gutting them, never have seen a pee bladder. Where does the pee come out? Same place as the poop I guess?

osmoregulation (fluids/salts/dissolved gases) primarily exchanged at gills and secondarily through GI system

You'd never see the urinary bladder cleaning a fish, but they do have one. In the vent of the fish there are two openings; one for the "poop" that is connected to the digestive tract (anus), and the second (urogenital aperture),where the "pee" comes out, is connected to the urinary and reproductive systems.