Ocean warming is one of the most pressing issues for marine species worldwide. Most marine species are ectothermic, and they rely on the conditions of the surrounding environment for appropriate development and reproduction. Thus, increasing temperatures usually lead to higher energetic requirements, and if these demands are not met, there can be cascading negative effects on key physiological processes. Further, ocean warming is also leading to the degradation of coral reef ecosystems, which is leading to a progressive simplification of tropical habitats. Despite recent advances in understanding how adaptation and plasticity (both developmental and transgenerational) can lead to compensation to environmental stressors, questions remain on the synergistic effect temperature and habitat simplification can have on marine species from both a molecular and physiological perspective. With this in mind, this seminar will focus on the molecular, behavioral and physiological responses to temperature fluctuations and habitat simplification in tropical fishes.