Clarias Explained

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, and is about the ability of the fish to live for a long time out of water.

Taxonomy

Clarias is paraphyletic. A species of Heterobranchus (H. longifilis) clusters deeply inside the Clarias group.^[1]

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.^{[2] [3]} The genus is found in Southeast Asia and East Asia westwards through India and Asia Minor and in Africa.^[4] The diversity of these catfishes is highest in Africa.^[5] Some (notably the walking catfish) have become pest species where they were accidentally introduced, 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. Many species also have a large, accessory breathing organ composed of modified gill arches.^{[2] [4]} Also, only the pectoral fins have spines.^[6]

Species

There are currently 62 species recognized in this genus:

African species

Asian species

Fossil species

• Clarias falconeri Lydekker, 1886, from India

Importance to economy

Many species are of great economic importance in fisheries and fish culture.^[5]

Invasive species

Clarias catfish and primarily Clarias batrachus (walking catfish) have been introduced to many different areas of the world, causing problems for native wildlife. The effect of the 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.^[15] Countries where one or several Clarias species have been introduced include Indonesia, the United States, Hong Kong, China, the UK,^{[16] [17]} Papua New Guinea, Guam, Taiwan, Thailand, and Cuba.

Notes and References

1. Mwita. CJ. Nkwengulila, G.. 2008. Molecular phylogeny of the clariid fishes of Lake Victoria, Tanzania, inferred from cytochrome b DNA sequences. Journal of Fish Biology. 73. 1139–1148. 10.1111/j.1095-8649.2008.01935.x. 5. 2008JFBio..73.1139M .
2. Clarias insolitus, a new species of clariid catfish (Teleostei: Siluriformes) from southern Borneo. Heok Hee. Ng. Zootaxa. 284. 1–8. 2003. 10.11646/zootaxa.284.1.1. 2009-06-24. free.
3. Clarias microstomus, a New Species of Clariid Catfish from Eastern Borneo (Teleostei: Siluriformes). Heok Hee. Ng. Zoological Studies. 40. 2. 158–162. 2001. 2009-06-24. dead. https://web.archive.org/web/20110719125046/http://zoolstud.sinica.edu.tw/Journals/40.2/158-162.pdf. 2011-07-19.
4. Clarias batu, a New Species of Catfish (Teleostei: Clariidae) from Pulau Tioman, Peninsular Malaysia. Kelvin K. P.. Lim. Ng, H. H.. The Raffles Bulletin of Zoology. 1999. 6. 157–167. 2009-06-24. dead. https://web.archive.org/web/20110606051050/http://rmbr.nus.edu.sg/rbz/biblio/s6/s6rbz157-167.pdf. 2011-06-06.
5. Description of a New Clarias Species from Southeast Asia Based on Morphological and Genetical Evidence (Siluriformes, Clariidae). Guy G.. Teugels. Sudarto. Pouyaud, Laurent. Cybium . 2001. 25. 1. 81–92. 2009-06-24. dead. https://web.archive.org/web/20101226201806/http://www.mnhn.fr/sfi/cybium/numeros/pdf/251pdf/11.teugels.pdf. 2010-12-26.
6. Description of a New Clariid Catfish, Clarias pseudonieuhofii from West Borneo (Siluriformes: Clariidae). Sudarto. Teugels, Guy G. . Pouyaud, Laurent. Zoological Studies. 43. 1. 8–19. 2004. 2009-06-24. 2018-06-13. https://web.archive.org/web/20180613212303/http://zoolstud.sinica.edu.tw/Journals/43.1/8.pdf. dead.
7. Clarias lamottei (Siluriformes, Clariidae), a Natural Intergeneric Hybrid from West Africa . 12 April 2023 . Guy G. Teugels . amp . Cybium . 2003 . 27 . 1. 11–15.
8. Web site: A New Species of Air-Breathing Catfish (Clariidae: Clarias) from Salonga National Park, Democratic Republic of the Congo . 11 April 2023 . Maxwell J. Bernt . Melanie L.J. Stiassny . amp . American Museum Novitates 2022(3990) . Bernt, Maxwell J. & Stiassny, Melanie L.J. . 2022.
9. Web site: Two New Species of Catfishes of the Genus Clarias from Borneo (Teleostei: Clariidae) . 11 April 2023 . Ng Heok Hee . amp . Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Crescent, Singapore . H. H. Ng . 1999.
10. Ng, H. H. . Dang, K. H. . Nguyen, V. T. . amp . 2011 . Clarias gracilentus, a new walking catfish (Teleostei: Clariidae) from Vietnam and Cambodia . Zootaxa . 2823 . 61–68 . 10.11646/zootaxa.2823.1.4.
11. Description of two new Clarias species from Borneo (Siluriformes, Clariidae) . 11 April 2023 . Tomy Sudarto . Guy Teugels . Laurent Pouyaud . amp . Cybium . March 2003.
12. H. H. Ng . Hadiaty Rk . Renny Kurnia Hadiaty. 2011. Clarias microspilus, a new walking catfish (Teleostei: Clariidae) from northern Sumatra, Indonesia. Journal of Threatened Taxa. 3 . 3. 1577–1584. 10.11609/JoTT.o2386.1577-84 . https://web.archive.org/web/20120322211723/http://www.threatenedtaxa.org/ZooPrintJournal/2011/March/ng.htm . 2012-03-22.
13. Clarias nigricans, a New Species of Clariid Catfish (Teleostei: Siluriformes) from Eastern Borneo. The Raffles Bulletin of Zoology. 2003. 51. 2. 393–398. Heok Hee. Ng. 2009-06-24. 2009-02-19. https://web.archive.org/web/20090219053936/http://rmbr.nus.edu.sg/rbz/biblio/51/51rbz393-398.pdf. dead.
14. Ng, H.H. . Kottelat, M. . 2014. Clarias serniosus, a new walking catfish (Teleostei: Clariidae) from Laos. Zootaxa. 3884. 5. 437–444. 10.11646/zootaxa.3884.5.4 . 25543801 .
15. Web site: Clarias batrachus (Linnaeus, 1758). Nonindigenous Aquatic Species . USGS.
16. News: Walking catfish spotted in the Thames by angler. 18 March 2009. The Telegraph.
17. News: Environment Agency warning over Clarias Catfish found in River Tonge, Bolton. 19 July 2017. The Bolton News.