Influence of dietary amino acid patterns on the free amino acid contents of blood and muscle of rainbow trout (Salmo gairdnerii R.).

1. Groups of rainbow trout were given one or other of two diets that differed in amino acid profile for two months; concentrations of free amino acids in whole blood and latero-dorsal muscle were then measured. The effects of temperature (12 and 18 degrees C in freshwater) and salinity on the concentrations of free amino acids in these tissues were also observed. 2. Although both diets apparently met the essential amino acid requirements of the trout and were isoenergetic, they nevertheless had different nutritional values for trout. 3. Patterns of free amino acids in tissues of trout given the two diets were different. Blood and muscle amino acid fractions were affected differently by changes in dietary amino acids.