COMPONENTS OF THE ENERGY BUDGET IN THE EUROPEAN MINNOW, PHOXINUS PHOXINUS (L.) IN RELATION TO RATION, BODY WEIGHT AND TEMPERATURE

The food consumption, faecal production, excretion, metabolism, growth and chemical composition of the minnow weighing 1—5 g were determined at various rations (starvation to ad libitum) and temperatures (5—15℃). The maximum rate of food consumption increased with increased body size and temperature. On the average, 6.5% of the food energy was lost in faeces, and 5.1% in the excretion of nitrogenous substances. The feeding metabolic rate increased with increased rate of feeding. At each temperature, the relationship between growth rate and ration was a decelerating curve. At maximum rations, growth rate increased with increased temperature; at restricted rations, growth rate decreased with increased temperature. The dry matter content and energy content of the fish increased with increased ration.