Zebrafish are increasingly important research animals whose welfare requirements are becoming better understood as their use expands.
Zebrafish welfare is at an early stage of scientific and regulatory development. Their use in research is growing rapidly, but welfare standards lag behind those for mammals. Adult zebrafish show evidence of pain and stress responses, and larvae — used in large numbers before regulatory protection thresholds — may also experience some form of nociception. The 3Rs principles apply to zebrafish research and their welfare deserves greater attention given the scale of use.