Zebrafish are the most widely used aquatic animal in biomedical research, and their welfare in laboratory settings is an important and growing scientific ethics concern.
Current UK regulation exempts zebrafish larvae under 5 days post-fertilisation from welfare oversight, despite evidence for pain responses emerging before this threshold. Water quality management in large zebrafish facilities is essential for welfare at scale. Anaesthesia and analgesia protocols for surgical procedures on adult zebrafish are an active welfare research area.