air-breathing catfish

Air-breathing catfishes are a fascinating group of fish that have developed the ability to breathe atmospheric air in addition to extracting oxygen from water. This adaptation allows them to survive in environments where water oxygen levels may be low or absent, such as stagnant ponds or during droughts.1

These catfishes possess specialized respiratory structures, which can be outgrowths of the pharynx, gill chamber, or digestive tract. For instance, some species have tree-like structures above their gill chambers, while others have lung-like sacs that extend along their bodies. The electric eel, for example, breathes air through its mouth, utilizing a highly vascularized lining for gas exchange. Other catfishes swallow air into their digestive tract, with the stomach or intestine serving as an auxiliary respiratory organ. This remarkable ability highlights the diverse evolutionary strategies fish employ to thrive in various aquatic habitats.12