Official name: Breede River Redfin
Derivation of the scientific name: Its scientific name comes from the Ancient Greek pseudos meaning false and the Latin barbus meaning beard, referring to the barbels or barbs. Pseudobarbus was described by Smith (1841) as a subgenus of Barbus. Nearly 150 years later, the subgenus was raised to full generic status.
Common names: Breede River redfin, Barrydale redfin, Burchell’s redfin, Tradouw redfin (Eng.); Burchell-se-rooilerkie (Afr.)
Known for its red fins and darker spots along the midline of the body, Pseudobarbus burchelli is one of the Critically Endangered Cape Floristic Region (CFR) fishes.
How to recognise the Breede River redfin
A Breede River redfin is a small, medium-sized, pigmented riverine fish that gets its name from its red fins. Rays of the primary dorsal fin are soft and flexible, and scales are striated in a radiating pattern. It is also defined by the presence of dark spots along the midline of the body, which serve as part of the sensory organs that detect movements and vibrations. Juveniles and young adults are olive brown and tend to have scattered spots They can grow up to a maximum of 14 cm, with the females growing longer than the males. During the breeding season, the fish is characterised by tubercules on the head, bright red fins and contrasting patterning.
The Breede River redfin facilitates movement by flexing its body and moving its tail back and forth. To move forward through the water, the fish expands its muscles on one side while remaining relaxed on the other. Caudal fins are used by fish to push themselves through the water.
Sound production in this species is associated with the breeding season for the establishment of territories and egg-laying sites. Most sound production has been observed in males in defense of their territories in between cobbles and rocks. They appear to be guarding rocks and cobbles where they make a rapid chirping sound in a seemingly aggressive display. Further research on this species is required to elaborate more on their sound production.
Breede River redfins are endemic to the Touw and Breede river systems, as well as adjacent smaller river systems in the Western Cape, South Africa. Their discontinuous distribution range in these river systems is largely influenced by the absence of non-native fish and by the distribution of food sources.
Breede River redfin populations inhabit clear, oligotrophic mountain streams, which is a typical habitat for many redfin species. The tributaries exhibit minimal mineralisation and slight suspension, providing refuge to a variety of small-bodied animals. The tributaries have a wide variety of macrohabitat types, including riffles and pools with the predominant bottom substratum being bedrock, boulders and cobbles. The Breede River redfin has been observed in such microhabitats but mostly in static pools with sand substrate.
Despite a lack of detailed studies, evidence suggests that the Breede River redfin forages around benthos and consumes an omnivorous diet. They eat small aquatic invertebrates, which are usually taken from the bottom as well as plant material such as algae and detritus.
Sex and life cycles
The breeding season occurs from September to February, with the major spawning possibly occurring between December and January. During the breeding season, males display prominent tubercles indicating that it is associated with reproductive function. Breede River redfin is a relatively short-lived species with females growing to a slightly larger adult size than males.
The Breede River redfin is known to be a gregarious species. The juveniles occur in large groups forming large shoals, but as they approach adulthood, they tend to form smaller groups and begin defending their territories.
The bigger picture
The Breede River redfins are a Critically Endangered species that play an important role in the ecosystem by acting as a flagship species for conservation projects for rivers that provide important ecosystem services. They also play an important role as biological indicators, as they provide an insight into the health of the rivers where they occur.
Friends and foes
It’s known that Breede River redfin interact with other fish species from the Cape Floristic Region, such as Sandelia capensis, Galaxias zebratus and Pseudobarbus skeltoni. The species can coexist due to resource partitioning and the occupation of different microhabitats.
The International Union for Conservation of Nature (IUCN) lists Breede River redfin as Critically Endangered, mainly due to predation from alien fish species, such as largemouth bass (Micropterus salmoides) and banded tilapia (Tilapia sparrmanii). Other habitat degradation activities, such as water extraction, bulldozing of riverbeds and excess nutrients from agricultural activities, contribute to the decline of the species.
The genus Pseudobarbus is represented by seven described species in the CFR of South Africa and one species in the highlands of Lesotho. Seven species are described as Pseudobarbus afer, Pseudobarbus skeltoni, Pseudobarbus asper, Pseudobarbus phlegethon, Pseudobarbus quathlambae, Pseudobarbus burgi and Pseudobarbus tenuis. As one of the seven species, Pseudobarbus burgi is very closely related to the Breede River redfin.
Scientific name and classification
Official name: Breede River Redfin
Species: P. burchelli (A.Smith, 1841)
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Author: Nomndeni Nkosi