Research on freshwater farmed fish pain and welfare assessment has advanced rapidly. Understanding where the science now stands shapes regulatory and industry welfare standards for billions of fish.
The science of fish pain assessment has matured significantly since the early 2000s when fish sentience was routinely dismissed. The 2025 brain imaging research in rainbow trout, showing nociceptive processing through pathways analogous to mammalian pain circuits, represents a landmark confirmation of what behavioural research had long suggested. EFSA's 2023 conclusion that welfare-protective measures for fish are scientifically justified has regulatory implications across EU aquaculture and seafood processing. The development of validated behavioural welfare indicators - reproducible, practical and non-invasive - is the applied research frontier that will translate the science into farm-level practice. This progress matters for the billions of freshwater fish in aquaculture worldwide.