Have you ever heard the phrase “to drink like a fish?” Well, unless you’re a ocean dwelling species, that probably means staying sober. Because freshwater fish don’t drink! Saltwater fish on the other hand? They’re constantly drinking. But if some fish drink all the time and other fish don’t drink at all, we’re left with an obvious question: Do fish pee? What… you’ve never wondered that?! Water is essential to life as we know it. To keep their chemistry running smoothly, living things need just the right amount of water in their bodies.