Walking Catfish

The walking catfish is a freshwater species in the family Clariidae, native to Southeast Asia, including Thailand, Malaysia, Indonesia, and the Philippines. It is best known for its ability to breathe atmospheric air using specialized accessory respiratory organs, allowing it to survive out of water and move short distances across land, especially during rain, to reach new bodies of water. This adaptability has made it highly tolerant of poor water quality and low-oxygen environments such as ponds, swamps, and rice paddies. The species has also become established as an invasive species in parts of the southeastern United States, where it competes with native freshwater fish.

Distinguishing features include:

• Elongated, eel-like cylindrical body
• Mottled olive-brown, gray, or dark coloration, sometimes with light speckling
• Long, low dorsal and anal fins extending nearly the full body length without a separate adipose fin
• Broad, flattened head with four pairs of barbels
• Sharp, hardened pectoral spines used for locomotion on land
• Adults typically reach 25-40 cm Its air-breathing adaptation and long low fins running the length of the body distinguish it from most other freshwater catfish.

Walking catfish inhabit shallow, slow-moving, or stagnant freshwater habitats across Southeast Asia, including ponds, swamps, canals, rice paddies, and seasonal floodplain waters. They are highly tolerant of low-oxygen, warm water conditions generally between 24-30°C due to their accessory air-breathing organ. During dry periods or heavy rainfall, individuals can leave the water entirely and move overland to reach nearby pools, a trait that has aided its spread. Outside its native range, established populations occur in warm freshwater canals and wetlands in parts of Florida and other similar environments where conditions allow year-round survival.

This species is an opportunistic, mostly nocturnal forager that feeds on a wide variety of small invertebrates, organic debris, and plant material. Its accessory breathing organ allows it to gulp air at the surface and survive in oxygen-depleted water, and during periods of drought or heavy rain it can wriggle across damp ground using its pectoral spines and body undulation to relocate to more favorable habitat. Walking catfish are generally solitary outside of spawning periods, when adults construct simple nests in mud or vegetation for egg deposition. Its tolerance for harsh conditions and mobility across land have made it an effective coloniser of temporary and disturbed freshwater habitats.