Originally Posted by larryace
Do fish actually drink the water they breathe?
Yes, some actually do. The rest absorb it. It's actually interesting stuff, because it's one of the big ways salt-water and fresh-water fishes tend to differ. In general, freshwater fish absorb water through their gills and skin and rarely if ever "drink" water intentionally. Saltwater or ocean fish will usually actively "drink" water, processing out the salt. Even more interesting, is that there are fish who can live in both salt and fresh water; my understanding is that they alter their behavior when in salt water and drink only then.
I had a really cool marine biology teacher in school, very interesting guy and I remember a lot of what he had to say.