Airbreathing catfish

Airbreathing Catfishes
Clarias gariepinus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Siluriformes
Family:	Clariidae
Genera
Bathyclarias Channallabes Clariallabes Clarias Dinotopterus Dolichallabes Encheloclarias Gymnallabes Heterobranchus Heteropneustes Horaglanis Platyallabes Platyclarias Tanganikallabes Uegitglanis Xenoclarias

Airbreathing catfishes are fishes comprising the family Clariidae of order Siluriformes. There are about 14 genera and 100 species of clariids. All the clariids are freshwater species.^[1]

Distribution

Although clariids occur in Syria, southern Turkey and large parts of Southeast Asia, their diversity is the largest in Africa.^[2]

Description

Clariid catfishes are characterized by an elongate body, the presence of four barbels, long dorsal and anal fins, and especially by the autapomorphic presence of a suprabranchial organ, formed by tree-like structures from the second and fourth gill arches.^[1][2] This suprabranchial organ, or labyrinth organ, allows some species the capability of travelling short distances on land ('walking catfishes').^[1]

The dorsal fin base is very long and is not preceded by a fin spine. The dorsal fin may or may not be continuous with the caudal fin, which is rounded. Pectoral and pelvic fins are variously absent in some species. Some fish have small eyes and reduced or absent pectoral and pelvic fins for a burrowing lifestyle. A few species are blind.^[1]

Within the clariidae family there is a range of body forms from fusiform (torpedo-like) to anguilliform (eel-like). As species become more eel-shaped, a whole set of morphological changes have been observed, such as decrease and loss of the adipose fin, continuous unpaired fins, reduction of paired fins, reduction of the eyes, reduction of the skull bones, and hypertrophied jaw muscles.^[2]

Taxonomy

Heteropneustidae containing the genus Heteropneustes is considered by some to be a separate family and by others to be a subfamily. With Heteropneustidae and Clariidae as separate family, a recent paper groups these families into a superfamily called Clarioidea. Relationships of clarioids to other families remains uncertain.^[3]

Relationship to humans

Many clariids form a large part of artisanal fisheries. Clarias gariepinus is recognized as one of the most promising aquaculture species in Africa.^[4]

The airbreathing capacity of these fish has allowed such fish as Clarias batrachus to be an invasive species in Florida.^[1]

References

1. ^ ^{a b c d e} Nelson, Joseph S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7. 
2. ^ ^{a b c} Devaere, Stijn; Adriaens, Dominique; Teugels, Guy G.; Verraes, Walter (2006). "Morphology of the cranial system of Platyclarias machadoi: interdependencies of skull flattening and suspensorial structure in Clariidae". Zoomorphology 125 (2): 69. doi:10.1007/s00435-005-0012-7. 
3. ^ Sullivan, JP; Lundberg JG; Hardman M (2006). "A phylogenetic analysis of the major groups of catfishes (Teleostei: Siluriformes) using rag1 and rag2 nuclear gene sequences". Mol Phylogenet Evol. 41 (3): 636–62. doi:10.1016/j.ympev.2006.05.044. PMID 16876440. 
4. ^ Skelton, Paul H.; Teugels, Guy G. (1991). "A review of the clariid catfishes (Siluroidei, Clariidae) occurring in southern Africa". Rev. Hydrobiol. Trop. 24 (3): 241–260.