Explore the fascinating world of fish respiration in this Bidder Lecture from the SEB Gothenburg 2017 conference. Delve into the mechanisms and reasons behind breathing control in fish, presented by Steve Perry from the University of Ottawa, Canada. Learn about the benefits of hyperventilation, the role of neuroepithelial cells in sensing CO2 and ammonia, and the involvement of Rhesus glycoproteins in ammonia sensing. Discover how hypoxia-inducible factor 1-alpha (HIF1a) regulates the hypoxic ventilatory response and its potential connection to nitric oxide. Examine the crucial role of serotonin in chemoreception and its impact on the hypoxic ventilatory response in fish. Gain insights into cutting-edge research techniques, including studies on zebrafish larvae, that are advancing our understanding of fish respiratory physiology.