Do fish pee?

I am at a party. Conversation somehow turns to someone talking about how while in Cancun at the pool bar, the one IN the pool, there was a large group all drinking. One person was getting out often to relieve themselves in the proper way while in a pool (excusing oneself to the restroom). Upon returning they asked "Doesn't anyone else need to go to the bathroom?"

Everyone nodded and said "Yeah. We have!"

That is why I, when in a warm climate near the ocean, I prefer to swim in the ocean. Hotel pools and jacuzzis are little more than germ soup as far as I am concerned.

Of course someone quickly chimed in that fish poop in the ocean. I acknowledged that and said with the volume of water in the ocean, the concentration is considerably less than in a pool.

After the fish pooping, which we all know they do, everything poops, I asked if fish pee? Do fish drink water?

Do they? Do you care? Why should I care? If they do pee, do male fish stand up when they do so? And most importantly for the lady-fish, do they leave the seat up or put it down?