Amphibious fish are fish that are able to leave water for extended periods of time. About 11 distantly related genera of fish are considered amphibious. This suggests that many fish genera independently evolved amphibious traits, a process known as convergent evolution. These fish use a range of terrestrial locomotory modes, such as lateral undulation, tripod-like walking, and jumping. Many of these locomotory modes incorporate multiple combinations of pectoral, pelvic and tail fin movement. Many ancient fish had lung-like organs, and a few, such as the lungfish and bichir, still do. Some of these ancient "lunged" fish were the ancestors of tetrapods. However, in most recent fish species these organs evolved into the swim bladders, which help control buoyancy.Having no lung-like organs, modern amphibious fish and many fish in oxygen-poor water use other methods such as their gills or their skin to breathe air. Amphibious fish may also have eyes adapted to allow them to see clearly in air, despite the refractive index differences between air and water.
Lungfish : Six species, have limb like fins, and can breathe air. Some are obligate air breathers, meaning they will drown if not given access to breathe air. Some species will bury in the mud when the body of waterthey live in dries up, surviving up to two years until water returns.
Bichir :12 species, are the only ray-finned fish to retain lungs. They are facultative air-breathers, requiring access to surface air to breathe in poorly oxygenated water.
Rockskippers: These blennies are found on islands in the Indian and Pacific oceans. They come onto land to catch prey and escape aquatic predators, often for up to 20 minutes or more. Leaping blennies are able to jump over land using their tails. On Rarotonga, one species has evolved to become largely terrestrial.
Mudskippers : This subfamily of gobies is probably the most land adapted of fish. Mudskippers are found in mangrove swamps in Africa and the Indo-Pacific, they frequently come onto land and can survive in air for up to three and a half days. Mudskippers breathe through their skin and through the lining of the mouth and throat. This requires the mudskipper to be wet, limiting mudskippers to humid habitats. This mode of breathing, similar to that employed by amphibians, is known as cutaneous breathing. They propel themselves over land on their sturdy forefins. Some of them are also able to climb trees and skip atop the surface of the water.
Mangrove killifish : It can survive for about two months on land, where it breathes through its skin.
Eels: Some eels, such as the European eel and the American eel, can live for an extended time out of water and can also crawl on land if the soil is moist. The morayEchidna catenata sometimes leaves the water to forage.
Swamp eels, which are not real eels, can absorb oxygen through their highly vascularized mouth and pharnyx, and in some cases through their skin.
Airbreathing catfish : Amphibious species of this family may venture onto land in wet weather, such as the eel catfish, which lives in swamps in Africa, and is known to hunt beetles on land.
Labyrinth fish. This suborder of fish also use a labyrinth organ to breathe air. Some species from this group can move on land. Amphibious fish from this family are the climbing perches, African and Southeast Asian fish that are capable of moving from pool to pool over land by using their pectoral fins, caudal peduncle and gill covers as a means of locomotion. It is said that climbing gourami move at night in groups.
