|The Red-tailed Black Shark (E. bicolor) might only exist in captivity today|
|4 species (1 extinct in the wild)|
Epalzeorhynchos is a small ray-finned fish genus of the family Cyprinidae. Its members are – like some other cyprinids – known as "freshwater sharks" or simply "sharks". They are, however, freshwater members of the Osteichthyes lineage which is distinct from the Chondrichthyes lineage of sharks. The description of these animals as "shark" is most likely a reference to the shark-like shape of these popular cyprinids.
The genus Epalzeorhynchos may be placed in the tribe Garrini of the Labeoninae, or in subtribe Garraina of tribe Labeonini, if these are considered a tribe of subfamily Cyprininae. It is not yet resolved which is a more appropriate representation of their phylogeny.
Description and ecology
In size and shape Epalzeorhynchos generally resemble the Indian loaches (Botia), which although they are also cypriniforms, are far too distantly related to have anything other than convergent evolution be responsible for this similarity. Alternatively, Epalzeorhynchos might be considered a plumper version of Crossocheilus, which includes the well-known Siamese Algae Eater (C. siamensis) and is in fact a very close relative. Their coloration is also reminiscent of some Crossocheilus, or of the Mekong loaches (Yasuhikotakia), depending on the particular Epalzeorhynchos species.
Unlike actual sharks, Epalzeorhynchos "freshwater sharks" are Osteichthyes. Thus, they have gill covers that can actively pump water over the gills, enabling them to breathe comfortably while at rest. As typical for Garrini, they actually spend much time on or near the ground – though not quite as much as the related true gudgeons of the Gobioninae or the loaches of the cypriniform superfamily Cobitioidea. Still, they usually only move for prolonged distances during migration to their spawning grounds.
This genus feeds mainly on aufwuchs, detritus and small invertebrate and plant matter. Their mouthparts are not as apomorphic as that of many other Garrini; they do not have a pronounced rostral cap, but in addition to the two barbels on the rostrum they retain another pair of barbels at the rear edges of the lower maxilla. The upper lip carries a short bristly ridge, while the lower one has a sizeable hard edge with which they can scrape food off hard substrate like rocks or logs.
Three species are frequently, the others occasionally found in the aquarium fish trade. The demand for these colourful fishes is high, and breeding is almost impossible to achieve in the home aquarium. The popular species are thus bred on an industrial scale in Southeast Asia, but wild-caught fish are sometimes also traded due to a general lack of legal restrictions. This has in some regions drastically reduced stocks, and even led to local extinctions. However, the main problem is damming of rivers between the fishes' usual haunts and the breeding grounds. While otherwise a considerable take of wild Epalzeorhynchus could be sustained, dams will literally stand in the way of successful reproduction, and such isolated subpopulations are easily extinguished by overfishing. Water pollution is also problematic. Due to these threats, the Red-tailed Black Shark (E. bicolor) is very rare and perhaps even extinct in the wild already – though as it is still bred by fish traders in massive numbers, it is often found in aquaria even today.
- Epalzeorhynchos bicolor (H. M. Smith, 1931) (Red-tailed Black Shark, Redtail Shark, Red-tailed Labeo, Redtail Sharkminnow)
- Epalzeorhynchos frenatum (Fowler, 1934) (Rainbow Shark, Rainbow Sharkminnow)
- Epalzeorhynchos kalopterus (Bleeker, 1851) (Flying Fox)
- Epalzeorhynchos munensis (H. M. Smith, 1934)
- de Graaf et al. (2007), Stiassny & Getahun (2007)
- Kottelat (1996)
- Stiassny & Getahun (2007)
|Wikimedia Commons has media related to Epalzeorhynchos.|
- de Graaf, Martin; Megens, Hendrik-Jan; Samallo, Johannis & Sibbing, Ferdinand A. (2007): Evolutionary origin of Lake Tana's (Ethiopia) small Barbus species: indications of rapid ecological divergence and speciation. Anim. Biol. 57(1): 39-48. doi:10.1163/157075607780002069 (HTML abstract)
- Froese, Rainer, and Daniel Pauly, eds. (2011). Species of Epalzeorhynchos in FishBase. August 2011 version.
- Kottelat, M. (1996). Epalzeorhynchos bicolor. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 27 September 2009.
- Stiassny, Melanie L.J. & Getahun, Abebe (2007): An overview of labeonin relationships and the phylogenetic placement of the Afro-Asian genus Garra Hamilton, 1922 (Teleostei: Cyprinidae), with the description of five new species of Garra from Ethiopia, and a key to all African species. Zool. J. Linn. Soc. 150(1): 41-83. doi:10.1111/j.1096-3642.2007.00281.x PDF fulltext