Explore the compelling evidence for sentience in fish species through this 39-minute conference talk by Lynne Sneddon at the Society for Experimental Biology's Animal Satellite meeting. Delve into the concept of sentience, its implications for animal welfare, and the ethical considerations in experimental biology. Examine fascinating examples of fish behavior, including archfish, cleaner fish, and their capacity for positive and negative emotions. Investigate intriguing phenomena such as fear contagion and mirror recognition tests in fish. Consider the broader implications of accepting fish sentience on welfare practices and scientific research. Gain insights into novel research methods like skin swabbing and pain relief studies in wild animals. Conclude with key takeaway messages that challenge traditional views on fish cognition and emotion, encouraging a reevaluation of our understanding of these aquatic creatures.