hith the assistance of Roger Bills of the South
African Institute of Aquatic Biodiversity we have treaded
on new territory this month (April 2014) with a little known South
African catfish family, namely the Austroglanididae,which
comprises of only three species of
medium to large sized fishes, Austroglanis
barnardi (Skelton, 1981), Austroglanis gilli (Barnard,
1943) and Austroglanis sclateri (Boulenger, 1901). The
subject of our factsheet this month is the Barnard's Rock Catfish,
Austroglanis barnardi is the smallest
of the three species and prefers fast flowing, rocky habitats
of headwater streams. They seem to be restricted to cobble zones
of the lower gradient sections of tributary streams (Bills 1999).
This species is critically endangered and uncommon due to their
habitats being threatened by stream channeling, water extraction,
sedimentation and introduced small mouth bass (Micropterus
dolomieu Lacepède, 1802) and competition for food
as a result of the presence of species such as bluegill (Lepomis
macrochirus Rafinesque, 1819). It will probably never be
imported to our aquariums due to the above limitations. A.
barnardi only occurs in three tributary streams of the Olifants
system – all three are on the western side of the Cederberg
mountains (see map below). They have been recorded in recent times
in the mainstream of the Olifants River, but unsustainable water
extraction has caused these areas to dry up several times in the
last few years, suggesting that this area is recolonised from
the Heks population.
The placement of barbels on the lower jaw
is characteristic of this family, they are positioned far back
and off the jaws bones which is unusual, most catfishes are on
the jaw. Similar
to the Bagridae/Claroteidae where they were once formerly placed
in the Bagridae
family, but recognized in a separate family by Mo (1991) and de
Pinna (1998). Austroglanis catfishes live much longer
than we expected, the maximum age of 12+years for A. gilli
and 14+years for A. barnardi (Mthombeni,
V. G.; 2009).
Locality for Austroglanis
barnardi. Olifants system, Western Cape. Typical
habitat is shallow cobble riffles and runs. They don’t
seem to like deeper pools.
Aquarium Care: (Roger
Bills) I have kept all three species in aquaria – all quite
difficult to maintain in good condition. Best results were with
A. barnardi – I had them in a recirculating circular
tank. Packed peat into the filter and pushed the pH right down.
Fed them on worms mostly although I assume they generally eat
chironomids, mayflies and caddis mostly in the wild. They were
very aggressive with each other and seemed to maintain territories.
Roger Bills for his assistance in preparing this factsheet.
D1, 6; A iii-vi, 10-13. Fins short, rounded;
dorsal with weak spine, pectorals with short curved spine, adipose
fin large, caudal truncate. Humeral process stubby. Head depressed,
snout broad; three pairs of short barbels (nasals insignificant)
mandibulars on ventral side of head.
Golden brown with dark brown blotches.
Very aggressive with each other and seemed
to maintain territories so would need plenty of caves etc. laid
out so they would be out of site of conspecifics.
I did spawn them in the field – I
collected gravid fish and injected them with hormone and did get
them to spawn but did not get viable eggs. The eggs were however
adhesive and spawned in a single clump suggesting nesting. Their
aggressive behaviour would suggest to me that they are also guarders
of eggs. (R.Bills)
No discernable differences.
In their natural habitats, Austroglanis
species feed on benthic invertebrates, including insects
of the orders of Ephemeroptera (mainly Baetidae) and Diptera (mainly
Chironomidae). Fed them on worms mostly although I assume they
generally eat chironomids, mayflies and caddis mostly in the wild.
(Mthombeni, V. G.; 2009).
Austro = the south + Greek, glanis = a fish that can eat
the bait without touching the hook; a cat fish.
V. G.; 2009 The biology
of Austroglanis gilli and Austroglanis barnardi (Siluriformes:
Austroglanididae) in the Olifants system, Western Cape,
Skelton, P.H. 1993 A complete guide to
the freshwater fishes of southern Africa. Southern Book
Publishers. 388 p.
Scott L. E. P.; Skelton, P.H.;
Booth, A.J.; Verheust L.;
Harris, R.; Dooley, J.;
Atlas of Southern African Freshwater Fishes. South African
Institute for Aquatic Biodiversity, 2006 - Fishes - 303
Swartz, E., Bills, R. & Impson, D.
2007. Austroglanis barnardi. In: IUCN 2013. IUCN Red List
of Threatened Species. Version 2013.2. <www.iucnredlist.org>.
The primary rayed fin(s) on top of the body
Caudal fin: The
Anal fin : The median, unpaired, ventrally located
fin that lies behind the anus, usually on the posterior
half of the fish.
Adipose fin : Fleshy finlike projection
without rays, behind the rayed dorsal fin.
Pectorals : The paired fins just
behind the head.
Pertaining to the lower jaw. (mandibular barbels)
Nasal barbels: On top of the head, by the
nostrils. (nasal barbels)
Atlas of Southern African Freshwater Fishes.