Omani blind cave fish  (Garra barreimiae)

Classified as Vulnerable (VU) on the IUCN Red List (1).

The scarcity of fresh water habitats in the United Arab Emirates and Oman limits the number and variety of fish that are found there, with the Omani blind cave fish being the most common and widespread of the very few native fish species (2) (3). Small and dark in colour, the Omani blind cave fish is typically mottled brown, sometimes with more colourful red, white or blue markings in larger adults (2) (3), and has a thin, pale transverse line just behind the head, appearing to demarcate the head from the body. The body is relatively long, with a rather flat underside, and the head is wedge-shaped, with a blunt snout (2) and a specialised mouth plate on the underside, which acts as a suction device (2) (3). The scales are large and heavy (2).

Three subspecies of Omani blind cave fish have been suggested, Garra barreimiae barreimiae, G. b. shawkahensis and G. b. gallagheri (2) (3) (4), and a fourth, smaller subspecies, G. b. wurayahi, has also been proposed (4). Most notable, though, is the discovery in 1980 of a distinct cave-dwelling population which, like other cave-dwelling fish, is distinguished from its surface-dwelling relatives by its lack of pigmentation, decreased scales, and by the lack of externally visible eyes (5) (6) (7) (8), which leads to the species’ common name. In this cave-dwelling population, eyes are present in juveniles, but become covered in older fish, although individuals artificially exposed to light show increased development of the optic lobe in the brain (5) (6) (7).

The Omani blind cave fish is endemic to northern Oman, the United Arab Emirates and Bahrain (1) (2) (3) (6). The newly proposed G. b. wurayahi was recorded from Wadi Al Wurayah in the United Arab Emirates (4), while the cave-dwelling population occurs in a lake inside a deep cave on the south flank of the Jabal Akhdar mountains (7).

No wadis in the United Arab Emirates flow continuously at the surface throughout the year, so species such as the Omani blind cave fish have to be able to survive for extended periods in small, isolated pools. This is the only fish species seen in many wadis, and is able to survive regular drying out of its habitat (2) (3). It may also tolerate water temperatures of up to around 40 degrees Celsius, and salinity up to a third of that of sea water (3). The cave-dwelling population of Omani blind cave fish inhabits an underground freshwater lake (5) (7).

The Omani blind cave fish is a bottom-dwelling species, often hiding under stones or in crevices (9), and nuzzling over gravel and rock surfaces in a catfish-like manner. Juveniles tend to be more active, but all dart about frenetically when approached in a shallow pool, where predation risk may be high. The species has a tendency to move upstream, a behaviour which may aid dispersal when the wadis flow after rain. Individuals have been observed to climb several metres up waterfalls, and can even travel short distances out of water, moving across damp rock surfaces. The Omani blind cave fish feeds on detritus and algae, and will sometimes cannibalise its own eggs (2) (3). Larger individuals appear to maintain a temporary territory, within which the fish forages and chases away intruders (2).

Little is known about the life history of the Omani blind cave fish, although it is thought to lay tiny eggs in gravel, the eggs apparently able to hatch within 24 hours, but said to hatch only when conditions are favourable. Spawning may be triggered by rain or thunderstorms, which would ensure the rapid dispersal of the eggs (2) (3). The cave-dwelling form is likely to feed on detritus washed into the cave, and possibly on bat guano and small invertebrates (8) (10). Like other cave fish, it may live longer than surface-dwelling individuals (8), and also shows other behavioural adaptations to underground life, such as a reduced tendency to form shoals, probably due to a reduced predation risk (10). There is evidence that, despite its lack of eyes, the cave form has retained some ability to respond to light (9).

The Omani blind cave fish is caught and eaten by people in the Hajar Mountains, typically using a portable sieve-like platform that is very effective at catching almost every fish in the area (2) (3). However, the impact of this on the wild population is unknown. The United Arab Emirates faces a number of environmental threats associated with increasing development, including increased industrial development, pollution, and ground water extraction, all of which may impact this species. The Omani blind cave fish may also be affected by increasing tourism to the wadis of the Hajar Mountains (11).

The Environment Agency - Abu Dhabi are working within the United Arab Emirates to conserve biodiversity and promote sustainable development (12), and one of the proposed subspecies of Omani blind cave fish, G. b. wurayahi, occurs in Wadi Al Wurayah, the United Arab Emirates’ first mountain protected area (4). The Omani blind cave fish is being bred in captivity at Chester Zoo and at a laboratory in Germany, as well as at the Breeding Centre for Endangered Arabian Wildlife in Sharjah, United Arab Emirates, which is attempting to learn more about the species (2) (13) (14). With relatively little currently known about the Omani blind cave fish, further research into its biology, distribution and populations will be needed before its conservation status can be better understood, and any necessary conservation measures put into place.

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about the Omani blind cave fish, and about conservation in the United Arab Emirates, see:

• Feulner, G.R. (1998) Wadi fish of the UAE. Tribulus, 8(2): 16-22. Available at:
  http://www.enhg.org/trib/tribpdf.htm
• Breeding Centre for Endangered Arabian Wildlife:
  http://www.breedingcentresharjah.com/
• Environment and Protected Areas Authority - Sharjah:
  http://www.epaa-shj.gov.ae/
• The Environment Agency - Abu Dhabi:
  http://www.ead.ae/en/