The food and feeding behaviour of Limnothrissa miodon (Boulenger, 1906) in Lake Kariba, Zimbabwe

Abstract

The feeding biology of the Lake Tanganyika sardine, Limnothrissa miodon (Boulenger, 1906) was studied to assess the quality and quantity of food items taken. Fish samples were collected at two hour intervals during a series of twenty-four hour trawling surveys in the Sanyati basin of Lake Kariba. The diurnal and nocturnal consumption trends for each food item were determined. Fish stomach contents were first analysed under a dissecting microscope and subsequently on an inverted regular high power Nikon microscope. Food items were identified and quantified for frequency of occurrence and percentage composition. Limnothrissa miodon feeds mainly on the cladocerans Bosmina longirostris, Ceriodaphnia cornuta and Bosminopsis deitersi and the copepods Mesocyclops sp., Tropodiaptomus sp. and Thermodiaptomus sp. Aquatic insect larvae, rotifers and ostracods also occur infrequently in the diet. Several feeding peaks exist during a twenty-four hour cycle with an overall tendency to ingest food during the daytime. Limnothrissa miodon therefore mostly feeds on crustacean zooplankton and it is mainly a visual feeder that depends on availability of adequate light to locate its prey.