What you guys are talking about is aquaculture. I have a passive aquaponic farm. This is an actual practice that has just started to become more wide spread as more and more people ask the same question you just did. It can be as simple watering your lawn straight out without altering it, or you can use a syphon to collect fish poop and waste and mix with regular (or preferably ph 5.5 lowered) water to spray house plants or gardens. To working complete aquacultured farms in which a cycle of plants being watered by the nitrified waste water of the fish farm/ pond/ river system filters the water and sumps it back into the stock (fish) tanks starting the process over again. Granted this is a COMPLETELY understated overview of this practice, if you are truly interested, do some research and feel free to private message me any questions you think I can answer. YouTube has a few good quality videos of farm set ups and passive smaller systems. There's a growing amount of literature available on this topic as well- Hope you find a way to put that water to work, it's an interesting way to waste a few minutes on youtube....