Walking catfish

Walking catfish
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Siluriformes
Family:	Clariidae
Genus:	Clarias
Species:	C. batrachus
Binomial name
Clarias batrachus (Linnaeus, 1758)
Synonyms
Clarias assamensis Clarias punctatus Silurus batrachus

The walking catfish, Clarias batrachus, is a species of freshwater airbreathing catfish found primarily in Southeast Asia, so named for its ability to "walk" across dry land, to find food or suitable environments. While it does not truly walk as most bipeds or quadrupeds do, it has the ability to use its pectoral fins to keep it upright as it makes a sort of wiggling motion with snakelike movements.^[1] It can survive using this form of locomotion as long as it stays moist.^[1] This fish normally lives in slow-moving and often stagnant waters in ponds, swamps, streams and rivers (Mekong and Chao Phraya basins), flooded rice paddies or temporary pools which may dry up. When this happens, its "walking" skill allows the fish to move to other sources of water.

Characteristics and anatomy

Walking catfish are around 30 cm (a foot or so) in length and have an elongated body shape. Often covered laterally in small white spots, the body is mainly colored a gray or grayish brown.^[2] This catfish has long-based dorsal and anal fins^[2] as well as several pairs of sensory barbels. The skin is scaleless but covered with mucus, which protects the fish when it is out of water.

One main distinction between the walking catfish and native North American Ictalurid catfish is the walking catfish's lack of an adipose fin.^[2]

This fish needs to be handled carefully when fishing it out due to its hidden embedded sting or thorn-like defensive mechanism hidden behind its fins (including the middle ones before the tail fin, just like the majority of all catfish).

Magur - Clarias batrachus - sold in HAL market, Bangalore

Location and habitat

The walking catfish is a native of South East Asia including Malaysia, Thailand, eastern India, Sri Lanka, Bangladesh, Burma, Indonesia, Singapore and Brunei. It is also located in the Philippines and is called hito or simply "catfish" by the locals. During its season in the Philippines, it is widely distributed throughout the country and many consumers buy this product alive. This catfish is a tropical species and prefers a water temperature in the range of 10–28 °C (50–82 °F).

Walking catfish thrive in stagnant, frequently hypoxic waters,^[2] and are often found in muddy ponds, canals, ditches and similar habitats. The species spends most of its time on, or right above, the bottom surface, with occasional trips to the surface to gulp air.^[2]

Diet and eating habits

In the wild, the natural diet of this creature is omnivorous; it feeds on smaller fish, molluscs and other invertebrates as well as detritus and aquatic weeds. It is a voracious eater which consumes food rapidly and this habit makes it a particularly harmful invasive species.

As invasive species

In the United States it is an invasive species, which is now established in Florida and reported in California, Connecticut, Georgia, Massachusetts, and Nevada.

The walking catfish was imported to Florida, reportedly from Thailand, in the early 1960s for the aquarium trade.^[2] The first introductions apparently occurred in the mid-1960s when adult fish imported as brood stock escaped, either from a fish farm in northeastern Broward County or from a truck transporting brood fish between Dade and Broward counties. Additional introductions in Florida, supposedly purposeful releases, were made by fish farmers in the Tampa Bay area, Hillsborough County in late 1967 or early 1968, after the state banned the importation and possession of walking catfish. Aquarium releases likely are responsible for introductions in other states. Dill and Cordone (1997) reported that this species has been sold by tropical fish dealers in California for some time. They have also been spotted occasionally in the Midwest.

In Florida, walking catfish are known to have invaded aquaculture farms, entering ponds where these predators prey on fish stocks. In response, fish farmers have had to erect fences to protect ponds. Authorities have also created laws that ban possession of walking catfish.

As food

In Thailand this fish is known as Pla Duk Dan (Thai: ปลาดุกด้าน). It is a common inexpensive food item, prepared in a variety of ways, being often offered by street vendors, especially barbecued or fried.^[3]

Aquarium

A white variation with black patterns are commonly seen in aquarium fish trade. However this color variation is also prohibited where walking catfish are banned. Very well rooted plants and large structures that provide some shade should be included. Any tankmates small enough will be eaten.

See also

• Eel catfish
• List of freshwater aquarium fish species
• List of invasive species in the Everglades

References

1. ^ ^{a b} "Catfish 'walk' down street". Metro.co.uk. 2008-07-18. http://www.metro.co.uk/weird/article.html?in_article_id=225308. Retrieved 2008-07-18. 
2. ^ ^{a b c d e f} Robins, Robert H.. "Florida Museum of Natural History Ichthyology Department: Walking Catfish". Florida Museum of Natural History Ichthyology Department. http://128.227.186.212/fish/Gallery/Descript/WalkingCatfish/WalkingCatfish.html. Retrieved 2008-07-24. 
3. ^ Pla duk (Thai)

External links

• Ros, Wolfgang (2004): "Clarias batrachus - Erfolgreiche Froschwels-Nachzucht im Aquarium", Datz 57 (7): 12-15.
• Ros, Wolfgang (2006): "Clarias batrachus - Auslösen der Fortpflanzung bei Froschwelsen", Datz 59 (4): 33-37.