Feeding interaction of exotic Oreochromis niloticus (Linnaeus, 1758)
versus native Coptodon rendalli (Boulenger, 1896) in the upper Kabompo
River, northwest of Zambia.
Evaluating the feeding interaction of fishes is fundamental in
understanding the impacts of introduced species on the community
structure and ecosystem function of native species. In the Zambian
Rivers, studies have shown that native species has been impacted upon by
exotic Oreochromis niloticus, but few studies have investigated feeding
interactions between exotic Oreochromis niloticus which is omnivorous
and aquaculture preferred herbivorous native species (Coptodon rendalli)
in the natural distribution. We analysed the stomach contents of 368
specimens of the fishes to examine the feeding interactions between O.
niloticus and C. rendalli in the upper Kabompo River, northwest of
Zambia. Both species were grouped into size classes of <50,
51−100 and 101−150 mm total length (TL). However, in the size classes
51-100 mm and 151-100 mm O. niloticus had a larger dietary niche because
of its generalist diet than the native species, whose diet mainly
comprised of diatoms and algae. There was no significant ontogenetic
diet shift for both species, except for O. niloticus in size class
101-150 mm, whose diet consisted mainly of zooplanktons and micro fauna.
The results showed an interspecific competition in their size classes,
except for 101-150 mm size class, that indicated low dietary overlap.
This poses major impacts on food web structure and may explain
population decreases of some native species in the upper Kabompo River.
Future studies are required to further understand feeding interaction
between the exotic and other native fishes in the Kabompo River and
other rivers across African where the species coexist.