Why zebrafish welfare matters in research and how laboratory conditions can be improved.
Zebrafish welfare has been underregulated relative to their numbers because their small size, low cost, and exemption from traditional vertebrate welfare protections created an assumption that welfare was less important. The scientific evidence contradicts this assumption: zebrafish show nociception, stress responses, anxiolytic drug responses, and social behavior patterns that are relevant to welfare consideration. The sheer scale of zebrafish use — hundreds of millions annually — means that even modest per-individual welfare improvements have enormous aggregate impact. Regulatory progress in extending full vertebrate welfare protections to zebrafish at all life stages reflects the scientific consensus that these animals deserve welfare consideration proportionate to their demonstrated sentience.