Flexi Says: Most fish cannot breathe in air. Instead, they breathe through specialized structures called gills which exchange oxygen and carbon dioxide with the water. Gills only work when water is flowing over them. The vast majority of fish species cannot survive in air for lack of oxygen. However, there are a number of fish species that are capable of breathing air. The ways that these species obtain oxygen from air are highly varied. Some, such as various species of catfish, take in air and absorb oxygen through the lining of their digestive tracts. Others, like the mudskipper, absorb oxygen through their skin, much like non-vertebrate chordates
