Banded neolebias  (Neolebias lozii)

Classified as Critically Endangered (CR) on the IUCN Red List (1).

Discovered as recently as 1993, this small, rare fish is only found in two streams within the Upper Zambezi River floodplain, Zambia. The most distinguishing feature of the banded neolebias is a series of nine to twelve vertical, black bars running down each side of its body. Each bar is clearly defined at the centre, becoming increasingly blurred towards the ends. The body of this species is light olive or olive-grey, darker on the upperparts and much lighter, or even white, on the underside. The eyes are a silvery-grey colour with some specimens possessing an orange tint around the outside. All of the banded neolebias’ fins are transparent and coloured with a faint orange hue, with the exception of the pectoral fins which are entirely colourless (2).

This Critically Endangered fish is restricted to Kataba creek and its tributary, Sianda creek. These two small streams are found on the edge of the Barotse floodplain region of the Upper Zambezi River in western Zambia (1).

The banded neolebias is found at the edges of small streams under and amongst dense, floating mats of vegetation (1), as well as amongst submerged and emergent plants (2).

Owing to its small size, low abundance and limited distribution, the banded neolebias escaped detection until 1993, and little is currently known about its life history. Because of its diminutive size, small mouth and teeth, it has been concluded that the banded neolebias feeds on tiny aquatic invertebrates.

Given the nature of its preferred habitat, it is somewhat surprising that the range of the banded neolebias is so restricted. During the rainy season (generally December to April), the streams that the banded neolebias occupies, along with others on the upland margins of the Barotse floodplain, burst their banks and flood the expansive, surrounding grasslands. However, surveys on the Barotse floodplain during the rainy season have failed to find any evidence of the presence of the banded neolebias (2).

Despite the absence of any immediate threats to the banded neolebias, its low abundance and highly limited range mean that it may be highly susceptible to future pressures. Although the region is still relatively undisturbed, Sianda creek and parts of Kataba creek have already been developed into canals, reducing habitat availability for the fish. As the local human population increases, it is likely that intensified agriculture will lead to pollution of the banded neolebias’s habitat from fertilisers and herbicides. Deforestation will also be likely in the area surrounding the floodplain, causing various negative effects on the local ecosystem (1).

An additional potential threat to this species is the invasion of its habitat by the Nile tilapia (Oreochromis niloticus). This fish has proved to be problematic after invading other ecosystems, outcompeting native species, as well as eating vegetation, fish eggs and even small fish (3). With farmed populations of this species now within the Zambezi River’s catchment, there is a strong possibility that it could eventually reach the habitat of the banded neolebias (1).

There are currently no measures in place to protect the banded neolebias. However, various strategies have been proposed, including further study of its biology, assessments of its population and analysis of its threats. In addition, the creation of a protected area encompassing its range, continual population monitoring, and prevention of invasion by the Nile tilapia have been recommended (1). The banded neolebias is a tiny fish with no economic value (4), nevertheless, as a unique component of Zambia’s biodiversity, its preservation is important.

To learn more about aquatic biodiversity and conservation in southern Africa see:

• The South African Institute for Aquatic Biodiversity:
  www.saiab.ac.za