Flexi Says: Although the vast majority of fish species obtain oxygen from water using gills, there are a number of fish species that are also 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 shown in Figure below, absorb oxygen through their skin, much like non-vertebrate chordates.
