Résumé
Fishes employ many and diverse strategies to increase oxygen transfer from the environment to their tissues and/or avoid problems associated with hypoxia. Some of these responses can be activated quickly (e.g., hours, days), whereas others are developmentally plastic and/or genetically fixed. Short‐term physiological and biochemical responses provide regulatory mechanisms to deal with variable oxygen in habitats. Behavioral responses can provide additional flexibility to mitigate exposure to hypoxic stress, and many occur at levels of aquatic oxygen availability far higher than lethal levels. Fish may avoid hypoxic areas through movement or they may compensate for hypoxia through air‐breathing or aquatic surface respiration (ASR), ventilating their gills with water from the air–water interface. As a result, behavioral responses to hypoxia can influence other critical components of the behavior of fishes in their environment, including habitat use and selection, predator–prey interactions, competitive interactions, and patterns of aggregation. In this chapter, we review behavioral responses to hypoxia, including aquatic surface respiration, air‐breathing, changes in spontaneous activity, and parental care. We then consider the role of hypoxia in modulating ecological interactions, in particular the interaction between predator and prey. Hypoxic alterations to predator–prey interactions can influence other components of the food web and assemblage structure; so predicting whether predator or prey is the beneficiary of hypoxic stress is fundamental to understanding community level impacts of hypoxia, whether natural or anthropogenically induced.