J. F. Steffensen, Jacob L. Johansen, Paolo Domenici
Fish depend on swimming to perform behaviours essential to survival and fitness, including predator evasion, prey capture, territorial defense and migration. Early research on fish swimming often examined isolated components such as behaviour, biomechanics or physiological performance, whereas more recent work adopts integrative frameworks that link these processes across biological scales. In this Commentary, we outline how more than 20 years of teaching a research-intensive course on fish swimming has allowed the participating students to ask questions about how fish swimming can be modulated by interacting internal and external factors. Using complementary approaches, including high-speed kinematics, swim-tunnel respirometry and behavioural assays under controlled stressors, student-led projects examined diverse questions. These ranged from the determinants of escape responses and the energetics of steady and unsteady swimming to gait transitions, schooling dynamics and validation of methods used to quantify swimming energetics and behaviour. In addition to reviewing fish swimming kinematics and energetics, each Commentary section synthesizes the hypotheses tested, experimental approaches and insights gained from research undertaken during this course, while illustrating the process from the original idea to peer-reviewed, student-led publication.