Fig. 1. Muscle free amino acid (FAA) concentrations in rainbow trout alevins subjected to Experiment 1 treatments. (A) Examples of dispensable amino acids (DAA) in relation to dietary levels. (B) Examples of indispensable amino acids (IDAA) suggesting limitations in dietary peptide availability. (C) Amino acids involved in the proline–ornithine–arginine pathway. Data given as means ± S.D., two samples of 2 fish each were assayed per tank, three tanks per treatment (N=3 per group), except Free AA (N=2). The top graph (specific growth rate) is modified from Dabrowski et al. (2003). The lower parts of each figure (bars) show muscle concentrations of individual FAA (y₁ axis title to the left). The upper parts of each figure (broken lines) indicate the level of each amino acid in the diets (g 100 g^–1; y₂ axis title to the right). Significant differences between treatments (P<0.05) are indicated by differing letters. Figures with no letters next to the bars indicate non-significant one-way ANOVAs.