Barcode of Life Data Systems (BOLD) Stats Specimen Records:513 Specimens with Sequences:425 Specimens with Barcodes:414 Species:29 Species With Barcodes:28 Public Records:175 Public Species:13 Public BINs:16
They are found in inland waters throughout much of the Old World, and is one of the most widespread catfish genera in the world. The genus is found in Southeast Asia and East Asia westwards through India and the Asia Minor to Africa. The diversity of these catfishes is highest in Africa. Some (notably the walking catfish) have become pest species where they have been accidentally introduced.
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. Also, only the pectoral fins have spines.
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 clarias catfish varies from area to area but as they are predatory fish they often impact the local wildlife by eating other fish, birds and amphibians. In Florida the fish is causing problems by invading aquaculture farms and prey on the fish cultivated there. Countries where one or several Clarias species have been introduced include Indonesia, USA, Hong Kong, Taiwan, China, UK, Papua New Guinea, Guam, Taiwan, Thailand and Cuba.
^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 (5): 1139–1148. doi:10.1111/j.1095-8649.2008.01935.x.
The genus Clarias ScopoliZBK , 1777 is a group of air-breathing catfishes found in inland waters throughout much of the Old World.
They are easily identified by an anguilliform body, long-based dorsal and anal-fins, eye with free orbital margin and located dorsolaterally, large and well-developed neurocranium and the presence of an accessory breathing organ comprised of modified gill arches.
Although the bulk of ClariasZBK diversity is found in Africa (Teugels, 1986), 18 nominal species, 12 of which are currently considered valid (Ng, 1999; 2001), are known from Southeast Asia.
As recent studies have shown, the diversity of Southeast Asian ClariasZBK is higher than previously thought and undescribed taxa are still being described.
Heok Hee Ng (2003): Clarias insolitus, a new species of clariid catfish (Teleostei: Siluriformes) from southern Borneo. Zootaxa 284, 1-8: 1-1, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:8B2553DF-50B0-40B9-A2CF-AA08A243BF75