Describe the process of respiration in fish.
Fish have special organs for breathing. They are called gills. For breathing, the fish use the oxygen dissolved in water. They breathe by taking in water through their mouth and sending it over the gills. When water passes over the gills, the dissolved oxygen is extracted. The water then goes out through the gill slits. The extracted oxygen is absorbed by the blood and carried to all the parts of the body. The carbon dioxide produced during respiration is brought back by the blood into the gills for expelling into the surrounding water. The gaseous exchange in fish takes place in the gills.