Clanwilliam rock-catfish (Austroglanis gilli)
|Also known as:||Clanwilliam catfish|
|Genus||Austroglanis (1) (2)|
|Size||Length: 12.7 cm (3)|
Classified as Vulnerable (VU) on the IUCN Red List 2007 (1).
The Clanwilliam rock-catfish, found only in a few streams in South Africa (4), belongs to the family of Austroglanididae catfishes, which are characterised by their scaleless, elongated bodies (5). The Clanwilliam rock-catfish has a short dorsal fin, preceded by a strong spine, and a strong, serrated spine in the pectoral fins. Four pairs of barbels (fleshy projections used to taste and feel), hang down near the mouth (6).
The Clanwilliam catfish has been recorded from only 15 headwater streams of the Olifants River, in the Cedarberg Mountains, Western Cape Province, South Africa (2) (3) (4).
Occurs among rocks and cobbles and under banks in clear, flowing streams (3). Juveniles live in riffle habitats and then move into regions of deeper water as they mature (4).
Despite being vulnerable to extinction, little is known about the Clanwilliam rock-catfish. It feeds in on insects, especially the larvae of caddis and mayflies, and other small invertebrates taken from the bottom of the stream (3). Catfishes from the Austroglanididae family are generally nocturnal (2) (5).
The Olifants River system is one of the most heavily impacted in Africa (4). The river system, and therefore the species which inhabit it, are under threat from human activities and infestation by alien species. Damming, pesticide pollution, excessive extraction of water, the presence of alien fish such as bass, and infestation by invasive plants such as black wattle and blue gum have contributed to a dramatic decline in the quality of the riverine environment (7).
A two year project, funded by WWF South Africa, was undertaken in 1999 to gain further knowledge on the biology and population numbers of the Clanwilliam rock-catfish. This resulted in a recommendation for the Clanwilliam rock-catfish to be classified as Endangered on the IUCN Red List. A number of measures were also recommended to ensure the species survival; these include education of rural populations, protection of the streams, and removal of alien fishes and vegetation (4). More recently, a Water Research Commission project has been looking at developing conservation action plans for three species within the Cedarberg region including the Clanwilliam rock-catfish (2).
For further information on conservation work in South Africa see:
- WWF South Africa:
Authenticated (11/04/08) by Roger Bills, Curator Freshwater Fishes, South African Institute for Aquatic Biodiversity (SAIAB).
- Dorsal fin: the unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
- Invertebrates: animals with no backbone.
- Nocturnal: active at night.
- Pectoral fins: the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.
IUCN Red List (September, 2007)
- Bills, R. (2008) Pers. comm.
- Skelton, P.H. (1993) A Complete Guide to the Freshwater Fishes of Southern Africa. Southern Book Publishers, Bergvlei.
- Bills, I.R. (1999) Biology and conservation status of the Clanwilliam rock catfish and spotted rock catfish. Investigational Report No. 60. J.L.B. Smith Institute of Ichthyology, Grahamstown.
Coad, B.W. (July, 2007)
- Nelson, J.S. (1999) Fishes of the World. Third edition. John Wiley & Sons Ltd, New York.
CapeNature (July, 2007)