Oxygen consumption, food assimilation and energy content of southern African elvers ( Anguilla sp.)

Abstract

Juvenile eels (elvers) of three age classes were studied. Dry weights and ash-free dry weights were determined and expressed as percentages of wet weights. Mean values of 17.33% and 15.91% were obtained for dry weight and ash-free dry weight, respectively. Energy contents were determined, mean values being 4.26 kJ g −1 wet weight, 23.93 kJ g −1 dry weight and 26.08 kJ g −1 ash-free dry weight. Oxygen consumption of inactive elvers was measured and can be described by the equation: log oxygen consumption (μl g −1 h −1) = 3.19 − 0.39 log wet weight (mg). Uptake by active elvers was double that of inactive elvers. For a 127-mg elver, the efficiency of assimilation of food formula was 88.57% based on dry weights, and 92.70% based on energy. The elvers ingested 4.4% of their wet body weight in one feeding.