Walking Catfishes

Clarias is a genus of catfishes (order Siluriformes) of the family Clariidae, the airbreathing catfishes. The name is derived from the Greek chlaros, which means lively, in reference to the ability of the fish to live for a long time out of water.^[1]

Taxonomy

Clarias has been found to be paraphyletic. A species of Heterobranchus (H. longifilis) clusters deeply inside the Clarias group.^[2]

Distribution

They are found in inland waters throughout much of the Old World, and are one of the most widespread catfish genera in the world.^[3][4] The genus is found in Southeast Asia and East Asia westwards through India and the Asia Minor to Africa.^[5] The diversity of these catfishes is highest in Africa.^[6] Some (notably the walking catfish) have become pest species where they have been accidentally introduced, and particularly in Cuba, where their introduction was intentional.

Description

Clarias species are recognized by their long-based dorsal and anal fins, which give them a rather eel-like appearance. These fish have slender bodies, a flat, bony head, and a broad, terminal mouth with four pairs of barbels. They also have a large, accessory breathing organ composed of modified gill arches.^[3][5] Also, only the pectoral fins have spines.^[7]

Species

There are currently 62 species recognized in this genus:

African species

Clarias liocephalus

Clarias stappersii collected in Lavushi Manda National Park, Zambia by the South African Institute for Aquatic Biodiversity

• Clarias agboyiensis Sydenham, 1980
• Clarias albopunctatus Nichols & La Monte, 1953
• Clarias alluaudi Boulenger, 1906 (Alluaud's catfish)
• Clarias angolensis Steindachner, 1866
• Clarias anguillaris Linnaeus, 1758 (mudfish)
• Clarias buettikoferi Steindachner, 1894
• Clarias buthupogon Sauvage, 1879
• Clarias camerunensis Lönnberg, 1895
• Clarias cavernicola Trewavas, 1936 (cave catfish)
• Clarias dhonti Boulenger, 1920
• Clarias dumerilii Steindachner, 1866
• Clarias ebriensis Pellegrin, 1920
• Clarias engelseni Johnsen, 1926
• Clarias gabonensis Günther, 1867
• Clarias gariepinus Burchell, 1822 (North African catfish)
• Clarias hilli Fowler, 1936
• Clarias jaensis Boulenger, 1909

• Clarias laeviceps T. N. Gill, 1862
  • Clarias laeviceps dialonensis Daget, 1962
  • Clarias laeviceps laeviceps T. N. Gill, 1862
• Clarias lamottei (?) Daget & Planquette, 1967 ^[8]
• Clarias liocephalus Boulenger, 1898 (smoothhead catfish)
• Clarias longior Boulenger, 1907
• Clarias maclareni Trewavas, 1962
• Clarias macromystax Günther, 1864
• Clarias monsembulai Bernt and Stiassny, 2022 ^[9]
• Clarias ngamensis Castelnau, 1861 (blunt-toothed African catfish)
• Clarias nigromarmoratus Poll, 1967
• Clarias pachynema Boulenger, 1903
• Clarias platycephalus Boulenger, 1902
• Clarias salae Hubrecht, 1881
• Clarias stappersii Boulenger, 1915 (blotched catfish)
• Clarias submarginatus W. K. H. Peters, 1882
• Clarias theodorae M. C. W. Weber, 1897 (snake catfish)
• Clarias werneri Boulenger, 1906 (Werner's catfish)

Asian species

Clarias batrachus from Lumajang Regency, East Java, Indonesia

Clarias nieuhofii from East Kotawaringin, Central Kalimantan, Indonesia.

Clarias pseudoleiacanthus

• Clarias abbreviatus Valenciennes, 1840
• Clarias anfractus H. H. Ng, 1999 ^[10]
• Clarias batrachus Linnaeus, 1758 (Walking catfish)
• Clarias batu K. K. P. Lim & H. H. Ng, 1999 ^[5]
• Clarias brachysoma Günther, 1864
• Clarias cataractus Fowler, 1939
• Clarias dayi Hora, 1936
• Clarias dussumieri Valenciennes, 1840
• Clarias fuscus Lacépède, 1803 (Hong Kong catfish)
• Clarias gracilentus H. H. Ng, K. H. Dang & V. T. Nguyen, 2011 ^[11]
• Clarias insolitus H. H. Ng, 2003 ^[3]
• Clarias intermedius Teugels, Sudarto & Pouyaud, 2001 ^[6]
• Clarias kapuasensis Sudarto, Teugels & Pouyaud, 2003 ^[12]
• Clarias leiacanthus Bleeker, 1851
• Clarias macrocephalus Günther, 1864 (bighead catfish)
• Clarias magur F. Hamilton, 1822
• Clarias meladerma Bleeker, 1846 (blackskin catfish)
• Clarias microspilus H. H. Ng & Hadiaty, 2011 ^[13]
• Clarias microstomus H. H. Ng, 2001 ^[4]
• Clarias nebulosus Deraniyagala, 1958
• Clarias nieuhofii Valenciennes, 1840 (slender walking catfish)
• Clarias nigricans H. H. Ng, 2003 ^[14]
• Clarias olivaceus Fowler, 1904
• Clarias planiceps H. H. Ng, 1999 ^[10]
• Clarias pseudoleiacanthus Sudarto, Teugels & Pouyaud], 2003 ^[12]
• Clarias pseudonieuhofii Sudarto, Teugels & Pouyaud, 2004 ^[7]
• Clarias serniosus H. H. Ng & Kottelat, 2014 ^[15]
• Clarias sulcatus H. H. Ng, 2004

Fossil species

• Clarias falconeri † Lydekker, 1886, from India

Importance to economy

Yam pladuk fu (Thai: ยำปลาดุกฟู): shredded and deep fried Clarias (pla duk) catfish with salad

Pecel lele, an Indonesian-style deep fried Clarias (lele); usually sold as street food

Many of the species are of great economic importance in both fisheries and fish culture.^[6]

Invasive species

Clarias catfish and primarily Clarias batrachus (walking catfish) have been introduced to many different areas of the world, where they are causing problems for the native wildlife. The effect of introduction of these fish varies from area to area, but as they are predatory, they often affect the local wildlife by eating other fish, birds, and amphibians. In Florida, the fish are causing problems by invading aquaculture farms and preying on the fish cultivated there.^[16] Countries where one or several Clarias species have been introduced include Indonesia, the United States, Hong Kong, China, UK, Papua New Guinea, Guam, Taiwan, Thailand, and Cuba.

References