Evidence that fish experience pain has strengthened significantly in recent years, leading to growing recognition that analgesia should be provided during painful procedures in research settings.
Fish analgesia represents the frontier of laboratory welfare refinement. The question of whether fish feel pain has shifted from skepticism to scientific consensus that nociception occurs and that analgesics modify pain behavior — the same behavioral evidence used to justify analgesia in mammals. Yet fish analgesia remains underutilized in practice: many researchers do not provide analgesics before or after painful procedures, sometimes citing lack of validated protocols for specific species. The welfare principle that uncertainty should bias toward provision of pain relief rather than withholding applies with particular force when analgesics are cheap, feasible, and the alternatives are allowing potential suffering. Developing and disseminating species-specific analgesia protocols for commonly used fish species is a high-priority refinement opportunity.