Water is essential for all living beings that inhabit this planet, because it forms part, to a greater or lesser degree, of the composition of each one of them. In the formation of our body and in all biological processes, water is required. If our lungs were not always wet, we couldn't breath. If saliva didn't moisten food, we couldn't ingest it. If the water that forms part of blood didn't transport food throughout the entire body, our cells wouldn't be fed, they wouldn't breath, and they wouldn't be able to eliminate toxins either.
Water is the most abundant substance on earth, and it constitutes the ideal medium for life.
Each ocean, river, and lagoon has its own flora and fauna adapted to live there. For this reason, the majority of marine organisms cannot live in fresh water, just like river beings couldn't do so in the marine environment. Fresh waters also have a large diversity of organisms. Numerous plants that serve as food for fish. Insect larvae, snails, small crustaceans, and annelids that constitute the main food of carnivorous fish.