''Wallagonia leerii'', also known as the Great Tapah, helicopter catfish, and formerly the striped wallago catfish is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of catfish native to

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

. Its habitat ranges from the river drainages of

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

through the

Malayan peninsula The Malay Peninsula (Malay: ''Semenanjung Tanah Melayu'') is a peninsula in Mainland Southeast Asia. The landmass runs approximately north–south, and at its terminus, it is the southernmost point of the Asian continental mainland. The area ...

to the islands of

Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...

and

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. It can grow up to in length and weigh up to . It has been used as food in Southeast Asia since ancient times. Overfishing for its prized meat has caused the population to significantly decrease. Furthermore, the breeding migration pattern of this fish is especially vulnerable to damming, which has also decreased the wild population significantly. Until osteological research validated the genus ''

Wallagonia Wallagonia is a recently established genus of Silurid catfishes, containing 3 distinct species, all of whom are native to Southeast Asia: *''Wallagonia leerii'' *'' Wallagonia maculatus'' *'' Wallagonia micropogon'' For the longest time, these ...

'' in 2014, ''W. leerii'' was included in the genus ''

Wallago ''Wallago'' is a genus of catfishes order Siluriformes of the family Siluridae, or sheatfish. They are found in rivers throughout southern and southeastern Asia. The only extant species of this genus is '' Wallago attu''. Taxonomy The monophyly ...

''.Roberts, T.R. (2014): ''Wallago'' Bleeker, 1851 and ''Wallagonia'' Myers, 1938 (Ostariophysi, Siluridae), Distinct Genera of Tropical Asian Catfishes, with Description of †''Wallago maemohensis'' from the Miocene of Thailand. ''Bulletin of the Peabody Museum of Natural History, 55 (1): 35-47.'' The other two species of the genus ''Wallagonia'', the '' Lesser tapah'' from the

Mekong river The Mekong or Mekong River is a trans-boundary river in East Asia and Southeast Asia. It is the world's twelfth longest river and the third longest in Asia. Its estimated length is , and it drains an area of , discharging of water annuall ...

basin and the '' Spotted tapah'' from the

Kinabatangan river The Kinabatangan River ( ms, Sungai Kinabatangan) is a river in Sandakan Division, in northeastern Sabah, Malaysia. It is the second longest river in Malaysia, with a length of from its headwaters in the mountains of southwest Sabah, to its ou ...

basin on Borneo, are currently considered as distinct species. There are, however, strong suspicions that these may in fact be

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

of ''W. leerii'', as the sole difference seems to lie in a slightly different coloration.

Description

The Great Tapah is a large fish, commonly attaining lengths of 150 centimetres and a mass of up to 86 kilograms. The size of this fish however can easily exceed the aforementioned lengths. It is the second-largest catfish in its family and is only outsized by the

wels Wels (; Central Bavarian: ''Wös'') is a city in Upper Austria, on the Traun River near Linz. It is the county seat of Wels-Land, and with a population of approximately 60,000, the eighth largest city in Austria. Geography Wels is in the H ...

Giant pangasius The giant pangasius, paroon shark, pangasid-catfish or Chao Phraya giant catfish (''Pangasius sanitwongsei'') is a species of freshwater fish in the shark catfish family (Pangasiidae) of order Siluriformes, found in the Chao Phraya and Mekong b ...

and

Mekong giant catfish The Mekong giant catfish (''Pangasianodon gigas''; th, ปลาบึก, , ; km, ត្រីរាជ /''trəy riec''/; vi, cá tra dầu), is a large, threatened species of catfish (order Siluriformes) in the shark catfish family (Pang ...

. It has a short, rounded body and a long broad tail, the anal fin of the fish is about as long as the tail itself and it ends in a forked

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

. The pelvic fins of the fish are small, and there are no dorsal spines on it. The Great Tapah possesses a noticeable hump, atop sits its dorsal fin, which is small and almost elliptical. The head of this fish is long, and remarkably wide with a huge lower jaw that extends beyond its

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

. The mouth of the catfish is inlaid with several rows of sharp teeth that enable it to grip prey. It is a piscivore, primarily feeding on small fish which are snatched mid-swimming and consumed whole.

Threats

The Great Tapah faces a multitude of threats, as it is prone to destructive fishing, competing with invasive species, loss of suitable habitat, and dam construction that impact its lifecycle. Splitting of species within the complex may give doubts to the true abundance of the species, meaning it could be far more restricted than once thought.

Mating

In July, adults migrate downstream to flooded

grasslands A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natural ...

to spawn. At night, the eggs are spawned near the surface.

References

Siluridae Fish described in 1851 Taxa named by Pieter Bleeker {{Siluriformes-stub