Barbus anoplus

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Jim A. Cambray - Albany Museum, Somerset Street, Grahamstown, 6139 South Africa

Common names: Chubbyhead barb (E), Dikkop-ghieliemientjie (Afrikaans).

Conservation status:As a species in no immediate danger although populations are reduced by non-native piscivores such as black bass species.

Identification: Member of the Cyprinidae, D III + 7, A III + 5, LL 33-37 scales and scales have numerous radial striations. The primary dorsal ray is both simple and flexible. The common name, chubbyhead barb, is due to the characteristic blunt or rounded head profile. Normally a single pair of barbels. The males are easily recognizable during the breeding season with a brilliant golden breeding dress. The females remain a greyish-greenish hue similar to non-breeding males. In some populations males have a broad dark band along the body. Males can grow to 100mm SL while females can attain up to 120mm SL.

Distribution: This is a very widespread species and some populations live up to the DFC motto, "DESERT FISHES RULE: To boldly thrive where no other fish can make it!" The species, as presently known, has penetrated into many areas of South Africa from the highhveld Limpopo to upland Natal, Eastern Cape and the upper and middle Orange River basin which includes the arid Karoo. It also has a presence in the Olifants River (Western Cape), Gourits, Gamtoos, Sundays and Great Fish. I have witnessed this barb migrating up a mere 'trickle' of water in the Karoo, obviously taking a chance by penetrating into very small, temporary streams. This trait combined with its other life history traits (see below) would explain how it has come to be such a widely distributed species.

Abundance:This species can be locally very abundant. Introduced piscivorus fish reduce numbers in populations exposed to these non-native species.

Habitat and Ecology: This species has been studied in detail (Cambray, 1983a,b; Cambray & Bruton, 1984, 1985). As it is such as widespread species it occurs in a number of habitats, from clear, rocky upland streams to turbid man-made impoundments with silt substratums in the Karoo. It is a minnow and small size is known to be an adaptation to a highly variable environment as it makes new food sources available by allowing ready access to spatially restricted habitats. Juveniles inhabit sheltered areas such as erosion gullies and vegetated areas in streams. When fish predators are absent it can grow to quite large sizes and even is found in the open waters of lakes and impoundments feeding on zooplankton (Cambray, 1983b). In areas with fish predators when cover, such as logs and vegetation, is present it will be found in their shelter. Due to its cryptic colouration, for most of the year, it survives in the presence of native predators such as the sharptooth catfish, Clarias gariepinus. Barbus anoplus has a life history style that enables it to colonize habitats of a temporary nature with alternating "booms and busts" in population size. In the Orange River the barb has to be adapted to a riverine system with erratic flows, devastating floods and high silt loads. Therefore traits such as early maturation in the first year of life, high reproductive effort, more than one clutch per year, quick growth and short inter-brood interval in phase with the optimal times of the year, would be advantageous for a small, short-lived species. Females can have a life span of 3-4 years compared to males with 2-3 years.

Reproduction: Barbus anoplus has both an early maturity, one year at 40mm FL, and a high reproductive rate which enables it to quickly colonize new areas. This reproductive strategy probably evolved in a seasonally fluctuating riverine environment and has been shown to be advantageous to this species ability to colonize impoundments and arid regions (Cambray & Bruton, 1984). Peak spawning usually occurs after periods of steady rainfall. A spawning migration is not necessary and fish can spawn locally if there is a rise in the water level and marginal vegetation is flooded, where the adhesive eggs are spawned (Cambray et al., 1978). However, some fish do undertake upstream spawning migrations after an increase in flow. There is a protracted reproductive season of five to six months, November to March/April during which an individual fish can have multiple clutches (Cambray & Bruton, 1984). Multiple clutches per season would also be advantageous in arid areas and decreases the chances of one or more generations being lost due to unfavourable conditions. A female of 63 mm FL can have up to 3250 eggs and the mature ova are 1 mm in diameter. Cambray and Bruton (1985) proposed that the cohort spawned late in the reproductive season does not spawn the next year and this prolongs the life of the year class by one year.

Threats: Habitat degradation, excessive water abstraction and introduced piscivorus species.

Conservation action: The various Departmental Conservation agencies should have trained staff to monitor fish populations and be able to react when signs show deterioration of the environment.

Conservation recommendations:As with any freshwater fish species in South Africa there is a need to consider fish reserves that will protect this gene pool for the future. Areas should be identified now so that introduction of non-native species can be restricted and also habitats can be conserved.

Remarks: There should be a thorough taxonomic study conducted on all the populations of this widespread species to assess if there is more than one species.

Literature:

CAMBRAY, J.A. l983a. Early development and larval behaviour of a minnow Barbus anoplus (Pisces: Cyprinidae). South African Journal of Zoology l8(4): 33l-336.

CAMBRAY, J.A. l983b. The feeding habits of minnows of the genus Barbus (Pisces: Cyprinidae) in Africa, with special reference to Barbus anoplus Weber. Journal of the Limnological Society of Southern Africa 9: l2-22.

CAMBRAY, J.A. 1984. The success of small cyprinid fishes of the genus Barbus in southern Africa, with special reference to Barbus anoplus. The Naturalist 28(2): 10-13

CAMBRAY, J.A. & BRUTON, M.N. l984. The reproductive strategy of a colonizing minnow, Barbus anoplus, in a man-made lake in South Africa. Journal of Zoology, London 204: l43-l68.

CAMBRAY, J.A. & BRUTON, M.N. l985. Age and growth of a colonizing minnow, Barbus anoplus, in a man-made lake in South Africa. Environmental Biology of Fishes l2(2): l3l-l4l.

CAMBRAY, J.A., HAHNDIEK, S. & HAHNDIEK, Q. l978. The juvenile fish population in the marginal areas of the Hendrik Verwoerd Dam. Journal of the Limnological Society of Southern Africa. 4(l): 2l-30.

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This page last modified:  09 December 2003