| Walking catfish | |
|---|---|
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| PiebaldC. batrachus; a commonmorph in aquaculture | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Siluriformes |
| Family: | Clariidae |
| Genus: | Clarias |
| Species: | C. batrachus |
| Binomial name | |
| Clarias batrachus | |
| Synonyms | |
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Thewalking catfish (Clarias batrachus) is a species of freshwaterairbreathing catfish native toSoutheast Asia. It is named for its ability to "walk" and wiggle across dry land, to find food or suitable environments. While it does not truly walk as mostbipeds orquadrupeds do, it can use itspectoral fins to keep it upright as it makes a wiggling motion with snakelike movements to traverse land.[2] This fish normally lives in slow-moving and oftenstagnant waters in ponds, swamps, streams, and rivers, as well as in floodedrice paddies, or temporary pools that may dry up. When this happens, its "walking" skill allows the fish to move to other aquatic environments. Considerabletaxonomic confusion surrounds this species, and it has frequently been confused with other close relatives.[3][4] One main distinction between the walking catfish and the native North Americanictalurid catfish with which it is sometimes confused, is that the walking catfish lacks anadipose fin.[5] It can survive 18 hours out of water.[6]
The walking catfish has an elongated body shape and reaches almost 0.5 m (1.6 ft) in length and 1.2 kg (2.6 lb) in weight.[3] Often covered laterally in small white spots, the body is mainly coloured a gray or grayish brown.[5] This catfish has long-baseddorsal andanal fins,[5] as well as several pairs of sensorybarbels. The skin is scaleless, but covered withmucus, which protects the fish when it is out of water.
This fish needs to be handled carefully when fishing it due to its embedded sting or thornlike defensive mechanism hidden behind its fins (including the middle ones before the tail fin, similar to the majority of all catfishes).
The walking catfish is atropical species native tomaritime Southeast Asia. The native range of trueClarias batrachus is confirmed only from theIndonesian island ofJava, but three closely related and more widespread species frequently have often been confused with this species. These areC. magur of northeast India andBangladesh, a likelyundescribed species fromIndochina, and another likely undescribed species from theThai-Malay Peninsula,Sumatra, andBorneo.[3][4] Both of these undescribed species have been referred to as,Clariasaff. batrachus.[3] At present, the taxonomic position of thePhilippines population (calledhito or simply "catfish" by the locals) is unclear, and it also is unclear whether South Indian populations areC. magur or another species.[4] As a consequence, much information (behavioral, ecological, related tointroduced populations, etc.) listed forC. batrachus, may be for the closely related species that have been confused with trueC. batrachus.[4] TrueC. batrachus,C. magur and the two likely undescribed species are all kept inaquaculture.[4]
Walking catfish thrive in stagnant, frequentlyhypoxic waters,[5] and often are found in muddyponds,canals,ditches, and similar habitats. The species spends most of its time on, or right above, the bottom, with occasional trips to the surface to gulp air.[5]
In the wild, this creature isomnivorous; it feeds on smaller fish,molluscs, and otherinvertebrates, as well asdetritus and aquatic weeds. It is a voracious eater that consumes food supplies rapidly, so it is considered harmful wheninvasive.[7]
Within Asia, this species has beenintroduced widely.[3] It has also beenintroduced outside its native range where it is considered aninvasive species. It consumes the food supplies of native fish and preys on their young. It also is regarded as an invasive species because they can destroy fish farms.
In theUnited States, it is established inFlorida.[8] It is reported inCalifornia,Connecticut,Georgia,Massachusetts, andNevada.The walking catfish was imported to Florida, reportedly fromThailand, in the early 1960s for theaquaculture trade.[5] The first introductions apparently occurred in the mid-1960s when adult fish imported as brood stock escaped, either from a fish farm in northeasternBroward 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 theTampa 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 this species has been sold by tropical fish dealers in California for some time. They also have been spotted occasionally in the Midwest.
In Florida, walking catfish are known to have invaded aquaculture farms, entering ponds where they prey on agricultural 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.
In 2017,Clarias spp. were recovered from theRiver Tonge, inBolton, England.[9]
In Indonesia, it is commonly referred to aslele, or when needing distinction;lele jawa orlele kampung, compared tolele dumbo orlele sangkuriang which refers to theintroducedC. gariepinus. It is the main ingredient in several traditional dishes, such aspecel lele andmangut lele.
In Thailand,Clarias aff. batrachus is known aspla duk dan (Thai:ปลาดุกด้าน). It is a common, inexpensive food item, prepared in a variety of ways. It is often offered by street vendors, especiallygrilled or fried.[10]
This fish is also one of the most common freshwater catfish in thePhilippines, which as aforementioned is known ashito in the local language. Despite this, current evidence ofClarias aff. batrachus populations from other regions of southeast Asia and India in relation towardsC. batrachus have not been thoroughly studied.[clarification needed]
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A white or calico color pattern is commonly seen in the aquarium fish trade.[11] However, this color variation also is prohibited where walking catfish are banned. Very well-rooted plants and large structures that provide some shade should be included in an aquarium with these fish. Any small tankmates will be eaten by this fish.
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