Stress levels in farmed Atlantic salmon need to be reduced to improve animal welfare and raise performance. However there are many factors causing stress and there are currently no reliable early warning tools that could be used to diagnose and take evasi ve action to minimise stress. Tests need to be easy to perform, inexpensive, highly sensitive, accurate, reproducible, and able to distinguish between different stress conditions. In this project we will utilise high throughput functional genomic tools to identify genes responding to feed availability and feed composition stresses, design and select a diagnostic test set for evaluation, check the reliability of the tests in an experimental situation and perform an on-farm field trial to assess the suitabi lity of the tests as early warning tools. The outcome of the project will be a set of transcriptome stress response tests that will allow farmers to make adjustments on-farm in order to optimise the level of performance and improve the welfare of farmed A tlantic salmon.