Barnard's rock-catfish (Austroglanis barnardi)
|Also known as:||Spotted rock catfish|
|Size||Length: up to 75 mm (2)|
Barnard’s rock-catfish is classified as Endangered (EN) on the IUCN Red List (1).
The extremely rare Barnard’s rock-catfish (Austroglanis barnardi) is one of three members of the Austroglanididae family of catfishes, all endemic to South Africa (3). Barnard’s rock-catfish can be identified by its flattened head and broad snout. The eyes are placed on the top of the head, rather than sides, while the mouth on the underside of the head is framed by fleshy lips. It also has three pairs of short barbels (3).
Barnard’s rock-catfish has short, rounded fins with relatively weak, curved spines on the dorsal and pectoral fins. It is golden brown in colour with large, dark brown blotches (3).
Barnard’s rock-catfish is endemic to South Africa where it has only been reported from three tributary streams of the Olifants river system (1). It has also been recorded in the mainstream of the Olifants River, near to the Heks tributary, but the water there frequently dries up and its presence is therefore dependent upon suitable water flow (1).
Barnard’s rock-catfishis known to favour fast moving water with a preferred depth of 10 to 60 centimetres (1) (4). It inhabits riffles along stream beds that largely made up of loose rocks and sand (3).
Only discovered in 1981, little is known about the biology of Barnard’s rock-catfish. However, species of the Austroglanis genus appear to be completely dependent on shallow stretches of fast flowing water for breeding and feeding (4). They are thought to feed on aquatic insects, benthic invertebrates and small fishes (5).
Although no estimates have been made of the overall Barnard’s rock-catfish population size, it is believed to be decreasing (1). Agricultural development in the form of stream channelisation and water extraction for crops is destroying the shallow and fast-flowing habitat required by this species for feeding and breeding (3). Unsustainable water extraction has caused the river to completely dry up in some areas (1).
Another major threat to Barnard’s rock-catfish is the introduction of predatory invasive alien species, such as the smallmouth bass (Micropterus dolomieu) (1) (3).
More research needs to be undertaken on the biology of this species, in particular relationships with alien predators and competitors, in order to better understand how best to conserve it (3). In addition, due to the specific habitat requirements of Banard’s rock catfish, special care must be taken in conservation strategies to maintain its preferred habitat of clean, fast-flowing water (3). The conservation of this species is linked with the overall management of the Olifants River system, and conservation of all three endemic Austroglanisspecies is of great importance in order to maintain the functioning of the small, endemic river community (3).
Discharge levels down the river and associated tributaries should be monitored to maintain the essential habitat for species such as Barnard’s rock-catfish (4). Further recommendations include a captive breeding programme in order to re-stock populations in the future (3).
Find out more on Barnard’s rock-catfish:
Fishbase - Barnard’s rock-catfish:
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- Barbels: fleshy projections near the mouth of some aquatic vertebrates.
- Benthic: relating to the lowermost region of a body of water such as an ocean or lake, or to the organisms that live there.
- Dorsal fin: the unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Invasive alien: species introduced deliberately or unintentionally outside their natural habitats where they have the ability to establish themselves, invade, outcompete natives and take over the new environments.
- Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.
- Pectoral fins: in fish, the pair of fins that are found on either side of the body just behind the gills. They are generally used for balancing and braking.
- Riffles: light rapids where water flows across a shallow section of river.
IUCN Red List (November, 2011)
Fishbase - Barnard’s rock-catfish (November, 2011)
- Bruton, M.N. (1996) Threatened fishes of the world: Austroglanis barnardi(Skelton, 1981) (Austroglanididae). Environmental Biology of Fishes, 45: 382.
- Gore, J.A., King, J.M. and Hamman, K.C.D. (1991) Application of the instream flow incremental methodology to Southern African rivers: Protecting endemic fish of the Olifants River. Water SA, 17: 225-236.
- Berra, T.M. (2007) Freshwater Fish Distribution. The University of Chicago Press, Chicago.