What are the features of the structure of the respiratory organs of fish associated with the habitat?

Man and many other land animals have lungs for gas exchange with the environment. They are available thanks to the atmosphere and oxygen in the form of a gas. The aquatic environment differs from the terrestrial one. Fish and many other inhabitants do not have lungs, since there is no air in the water. They get oxygen with the help of gills. These are organs that are able to receive oxygen from water and thanks to which carbon dioxide leaves the body of the fish. But some aquatic creatures are easy. They absorb air above water using the respiratory system.