Clarias batrachus is a species of freshwater catfish, commonly known as a walking catfish. Like many other types of catfish, it has the ability to breathe air. It also has another unusual skill — the ability to "walk" on land. Although it is originally native to parts of Southeast Asia, this catfish has been introduced to certain parts of the United States (US). Most environmental experts agree that it has the potential to cause damage to the local ecosystem, and it has been labeled an invasive species in many areas of the US.
The average length of this fish is typically around 1 foot (30.5 cm), but they have been known to grow to be as long as a 1.5 feet (45.7 cm). The scaleless body is smooth and protected by a thick mucus. White spots often cover the brown or gray body, which is topped by a long dorsal fin. The pectoral spines of this catfish are very sharp, and they are often used for moving across the land.
Walking catfish are known to take up residence in temporary waters, such as pools created by flooding during the rainy season. When these pools dry up, they can travel great distances in search of water. As long as the skin stays moist, walking catfish can survive out of water long enough to find a new home, at least temporarily. The name walking catfish is not technically correct. Instead of walking, this catfish moves along the ground like a snake or an eel. By flexing the sharp pectoral spines, this fish can pull its body along the ground.
Because it is considered to be a tropical species, the walking catfish typically prefers warm waters. It can be found in shallow, still waters, and because it an air-breathing catfish, it often thrives in water that is low in oxygen. Muddy, stagnant waters of temporary pools created by excess rain and flooding are usually the perfect environment for this species of fish.
Sometime during the 1960s, it is believed that the walking catfish was introduced into the United States from Thailand for use in aquariums. Shortly after this, some of these fish escaped, either by accident or because they were intentionally released. They are now established throughout many areas of Florida and Georgia, and possibly California and Nevada.
In many parts of the United States, especially Florida, importing or even possessing these live fish has been outlawed. Because of their extensive appetites, walking catfish can possibly have a detrimental impact on ecosystems. They will eat many of the smaller fish and vegetation, leaving little food for larger native fish. In some parts of Florida, walking catfish have been found in aquacultural ponds feeding on fish stocked there.
The walking catfish is an omnivore, snacking on a variety of different food items. Common diet items include small fish, aquatic insects, and vegetation. Ever the opportunist, the walking catfish has also been known to eat parts of dead fish.