Social hierarchies, growth and brain serotonin metabolism in Atlantic salmon (Salmo salar) kept under commercial rearing conditions.

Monitoring social interactions between individuals in large, high-density groups poses several challenges. Here we demonstrate that relative concentrations of serotonin (5-Hydroxytryptamine, 5-HT) and its principal catabolite 5-Hydroxyindoleacetic acid (5-HIAA) in brain tissue of individual fish reflect social organisation in large groups of farmed Atlantic salmon. In the central nervous system of vertebrates, the monoamine neurotransmitter/neuromodulator 5-HT is critical for maintaining adaptive physiological, cognitive and emotional processes.

Altered fatty acid compositions in atlantic salmon (Salmo salar) fed diets containing linseed and rapeseed oils can be partially restored by a subsequent fish oil finishing diet.

Atlantic salmon postsmolts were fed a control diet or one of 9 experimental diets containing various blends of two vegetable oils, linseed (LO) and rapeseed oil (RO), and fish oil (FO) in a triangular trial design, for 50 wk. After sampling, fish previously fed 100% FO, LO and RO were switched to a diet containing 100% FO for a further 20 wk. Fatty acid compositions of flesh total lipid were linearly correlated with dietary fatty acid compositions (r = 0.