Aquatic animals including fish species are being exposed to climate-related stressors such as temperature and hypoxia with increasing severity and frequency. Group living is an adaptive behaviour found in many species, including the majority of fish species, and associated with improved foraging success and protection from predators. As conditions change, however, individual motivations for group living may also change. Individual behaviours such as sociability, exploratory behaviour (boldness), and activity level, may be affected by climate-related stressors. This may lead to changes in group dynamics and shoal disruption. This study used rummy-nose tetra Hemigrammus rhodostomus as a model species, and tested boldness, sociability, and activity level in individuals under three conditions of temperature, and three conditions of oxygen level. Fish were then placed in groups of six under the same set of treatments, and group behaviour monitored for each individual. In this way, we hope to elucidate how individual changes in behaviour will impact group dynamics. We predict that individual sociability will be reduced, and boldness and activity increased, under increased temperature and low oxygen levels and that this will translate to reduced group cohesion under climate stressor conditions. We also predict significant interindividual variation in sociability, boldness, and activity level, and that this will impact the tendency of different individuals to associate together. Our study is the first, to our knowledge, to incorporate climate-related stressors into the study of effects of individual behaviour on group dynamics, and will provide much-needed information on a key adaptive behaviour in a changing world.