How do freshwater fish get water?

Freshwater fish obtain water through their gills. Gills are specialized respiratory organs that allow fish to extract oxygen from water. They consist of thin, filamentous structures called gill filaments, which are covered in tiny blood vessels. When a fish breathes, it draws water into its mouth and passes it over its gills. The water then flows out through the gill slits, which are located on either side of the head. As the water passes over the gill filaments, oxygen from the water diffuses across the blood vessels and into the bloodstream. At the same time, carbon dioxide from the bloodstream diffuses out into the water. This process of gas exchange allows fish to breathe in water.