The food of a community of East African freshwater fishes

Authors

  • J. L. Munro

    1. Zoology Department, University College of Rhodesia and Nyasaland, Salisbury, Rhodesia§
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    • *Based on a thesis accepted by the University of London in part fulfilment of the requirements for the degree of Doctor of Philosophy.


  • §Zoology Department, University of the West Indies, Kingston, Jamaica.

Abstract

Quantitative data on the food of the fishes inhabiting Lake Mcllwaine, Rhodesia, show that the feeding of the dominant species in this community (Clarias gariepinus (Burchell), Hydrocynus vittatus (Castelnau), Tilapia melanopleura Dumeril, Tilapia mossamhica Peters, Tilapia macrochir Boulenger, Labeo altivelis Peters, and Gnathonemus macrolepidotus (Peters)) covers a wide spectrum, and almost all elements of the potential food supplyare utilized. Exceptions are noted, however, and the introduction of the Indian carp, Catla catla (Cuv. & Val.), is advocated in order to utilize the large blooms of phyto- and zooplankton. The oligochaete, Branchiura cf. sowerbyi, which forms over 50% of the benthic biomass is also not utilized as a source of fish food. However, no fish species is known tofeed on oligochaetes to any large extent. Predation by the Tigerfish, Hydrocynus vittatus, is shown to have severe effects upon recruitment to the valuable Tilapia fishery, and the reduction of the abundance of H. vittatus by means of selective fishing techniques is advocated.

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