THE GROWTH AND FOOD RATION OF PISCIVOROUS BROWN TROUT (SALMO-TRUTTA)

1. In this study we examined how temperature, a major determinant of e nergy budgets and thus the biological success of ectothermal animals, affects growth and feeding rate of a teleost fish species. 2. Feeding experiments with piscivorous brown trout from the Norwegian River Laer dalselva were performed in the laboratory at water temperatures from 8 to 18-degrees-C, to estimate the optimal temperature for growth fed a t maximum rations. 3. Optimal temperature for growth was found to be a pproximately 16-degrees-C, which is 2-4-degrees-C higher than reported previously. 4. In contrast to earlier studies, the optimal temperatur e for growth was similar to the temperature at which maximum feeding r ates occurred. 5. Growth increased more rapidly with increasing temper ature for small and young fish than for large and old fish.