This report, comprising four studies, attempts to assess the consequences of climate change on the distribution of 23 fish species, as well as the effects of climate change on functional assemblages. The first study aimed to estimate the ecological requirements of these species, by modelling the occurrences of fish species with environmental factors, including temperature and precipitation. The confidence intervals around the occurrence–environment relationships were also computed, to identify in which environmental conditions the predictions are more uncertain. The second aim of this study was to compare two approaches so as to compute the expected metric values. The results showed that metrics computed from the species distribution models or from models related to functional trait variability or environmental conditions give relatively similar results. The first aim of the second study was to assess the consequences of climate change on the distribution of the 23 fish species. The logistic regressions computed in the first study were used to compute the probability of species presence under different climatic scenarios. These results demonstrated that cold- or cool-water species will be greatly and negatively affected by climate change, while warm-water species will be favoured. The uncertainty of the predicted probabilities reveal that for some species the effect of global change remains unclear, while for others only the magnitude of the response to climate change differs. These results were discussed from the perspective of river restoration and species conservation. The second aim of this study was to use the models developed to predict functional traits, so as to assess the expected drift of reference conditions. The results suggest that metrics based on species tolerance will be less represented in fish assemblages in the future, which will have important consequences on the use of current bio-assessment tools. The third part of this report is a case study on the Traun River in central Austria. A long-term survey of more than 30 years has been conducted in a station downstream of a lake outlet flow. Owing to climate warming, the water temperature in August has increased on average by 2.2°C. In reaction to this warming, a shift of species dominance and a large decline of the grayling population were observed. This study is a good illustration of the consequences of climate change on fish assemblages and of the necessity for water managers to take into account the effect of climate change when planning restoration measures. The fourth part of this report is a case study on the Seine basin in France. Species projections were made for the whole catchment area and demonstrate that cold-water species would be highly affected by climate change, especially in the decade of 2050–2060. Several species are predicted to be extinct up to this period, while some warm-water species are expected to expand their distributions throughout the catchment area. Human pressures were also included in the species distribution models to assess the potential effect of restoration scenarios on species distributions. The results highlight the potential benefits from these restoration measures, but mostly show that climate change will be the major factor driving species distributions, overcoming restoration measures.