This has to be one of the most viral set of videos on youtube. There are countless videos of people finding fish under dry land and just digging up the fish. Whats the secret? Whats the fish doing underground? Are they buried there?
Lets get on to details. The fish that you see in these videos are catfish. Catfish have a unique ability to survive in dry weather conditions. They can survive very low oxygen environments. The can also survive for a good amount of time outside water. This is possible with the help of suprabranchial organ(catfish). They even come out and move over land to another water body as part of survival.
During drought season, water beds dry up which they had inhabited earlier. To survive the scarcity of water, they move out in search of wetter areas. They are able to stay at small pools or holes of water that has just enough water, for months. In southern US noodling is a type of fishing where one used bare hands to catch the fish. Noodling is mostly done in these holes that catfishes dug out for survival.
Varieties of catfish also breathe through cutaneous respiration. For this, they will bury themselves in mud, encapsulate themselves in a mucus slime and stay that way, suspended for an entire year or more, absorbing oxygen through the permeable skin. These surviving fishes are dug up by people sometimes. These are mostly done in parts of Cambodia and nearby countries.
Even though some of these videos are made up by burying fishes inside mud, the technique is true and is practiced in some parts of the world.
Sources: (Safriel & Bruton 1984, Hecht et al. 1988)
(Bruton 1979c, Van der Waal 1998)