Barbus paludinosus, the "Straightfin barb," is a very widespread
species found from the Congo basin to Ethiopia
to Natal in South Africa.
Worthington (1933) reported 42 specimens
(of 38-100 mm SL) from Bar House, a locality on the shore of Lake
Malawi just east of the lake's outflow into the upper Shiré River.
It is probable that they were collected in a lakeshore swamp.
Jackson (1961: 549) asserted that this species
is "never [found] in the open waters of Lake [Malawi]," but it should be
expected in sheltered lake waters adjacent to swamps, like other species
from this habitat, as well as under the floating islands of swamp
vegetation seen frequently in the southern part of the lake
(Oliver & McKaye, 1982). Indeed, David Eccles
and I collected three individuals of B. paludinosus 1 August 1971
in the shallow intermediate zone at Chingubi Point, in the Southeast Arm
of the lake, where there was no adjacent swamp.
This barb is omnivorous, eating detritus, benthic crustaceans,
small fish, insects, phytoplankton, and aquatic plants (FishBase).
In parts of its range it can reach a standard length
(without caudal fin) of 15 cm (6 inches), but becomes sexually mature
at around 5 cm or 2 inches (maturity summary at FishBase).
According to the FishBase species summary,
B. paludinosus is "hardy" and "prefers quiet, well-vegetated waters
in lakes, swamps, and marshes or marginal areas of larger rivers and
slow-flowing streams.... Spawns amongst vegetation during summer."
Jubb (1967) describes its coloration
in life as "silvery ... with olive dorsal surface, fins yellowish or
pale olive. In large specimens a faint lateral stripe following the
dorsal contour can just be seen. This lateral stripe becomes accentuated
in specimens preserved in formalin, and in some ... the anterior
lateral line tubules are bordered with pigment."
Within the Lake Malawi Barbus fauna, B. paludinosus can
be identified by possessing all of the following characteristics
(modified from
Jackson, 1961: 595):
Striae (streaks) are radially arranged on exposed edges of the scales.
Last simple (unbranched) ray of dorsal fin is an enlarged, bony
spine and is serrated behind.
Coloration is plain silvery, lacking any spots or distinct,
dark midlateral stripe (but see photo and color description, above).
Additionally, there are at least 32 scales in the lateral line
(Jubb, 1967: 92), more than in most other
small barbs in the area.
The above illustration by Hilda M. Jubb, from
Jubb (1967), is used here with the generous
permission of Mr. A. T. Balkema of
A. A. Balkema
Publishers, Rotterdam.
