Shifts in the food of Nile tilapia, Oreochromis niloticus (L.) in Lake Victoria, Kenya

Abstract

Studies of the food of introduced Nile tilapia, Oreochromis niloticus (L.) with respect to size, habitat and season were conducted between November 1998 and October 2000 in Kenyan waters of Lake Victoria. Stomach contents of 1980 specimens collected by demersal trawl and seining were analysed. Nile tilapia originally known to be herbivorous, feeding mostly on algae has diversified its diet to include insects, fish, algae and plant materials. The major diet of fish <5 cm total length was zooplankton whereas bigger fish included a wider range of food items in their diet. There was spatial variation in diet with insects and algae dominating in the gulf and open water habitats respectively. There was no seasonal variation in the food items ingested and diel feeding regime indicated that O. niloticus is a diurnal feeder. The shift in diet could be due to ecological and environmental changes in Lake Victoria, which have been associated with changes in composition and diversity of fish and invertebrate fauna, emergence and dominance of different flora including water hyacinth Eichhornia crassipes (Mart.) Solms-Laub., and algae communities. The feeding habit of O. niloticus is discussed in the context of changes occurring in the lake. et invertébrée, à l'émergence et à la dominance d'une certaine flore, y compris la jacinthe d'eau, Eichhornia crassipes (Mart.) Solms-Laub., et de communautés d'algues. Les habitudes alimentaires d' O. niloticus sont discutées dans le contexte des changements survenus dans le lac.

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

“…The nature of the diet could be a possible explanation for such an inter-specific differences in concentrations. L. niloticus are exclusively piscivorous, consuming all available fish species including its own siblings whereas O. niloticus relies on zooplankton and macroinvertebrates (Ogari, 1984;Njiru et al, 2004). Earlier studies established that PCBs can have great variations among different fish, as well as within species depending on their feeding habits and trophic levels (Suedel et al, 1994;Vander Zanden and Rasmussen, 1996;Davis et al, 2002;van der Oost et al, 2003).…”

Management Implications of the Response of Two Tilapiine Cichlids to Long-Term Changes in Lake Level, Allodiversity and Exploitation in an Equatorial Lake

“…In studies where the inundation of the margins of African lakes by flood waters has occurred, the combination of decaying submerged terrestrial vegetation and the increased fluvial input of nutrients has resulted in increased production of detritus, phytoplankton, periphyton and zooplankton (Weyl 2007), with phytoplankton production also enhanced by the decreased turbidity (Guenther and Bozelli 2004). In response to the inundation and increased food resources, production of the tilapia species increases (McKaye et al 1995;Bwanika et al 2004;Njiru et al 2004;Peterson et al 2004Peterson et al , 2005Britton et al 2009). Increased growth rate and recruitment success following flood events have also been generally observed in cichlid populations (Dudley 1975(Dudley , 1979De Silva 1985;Weyl 2007) and appears evident in Lake Naivasha (Britton and Harper 2008).…”

Comparative Growth Performance and Proximate Nutrient Composition of Three Local Strains of Nile Tilapia (Oreochromis Niloticus L.) Collected From Different Locations in Uganda

“…The flesh lipid is controlled by the available nutrition [17] the feeding frequency, sex, and maturity of the fish [18][19][20][21][22][23]. The minerals composition of fish body is determined by the harvest waters [24][25][26]. The concentration of minerals in the harvest waters influences the content of those minerals in the habitat fish [27].…”