Zebrafish are among the most widely used vertebrate research models globally, but their welfare needs are often overlooked due to assumptions about fish sentience and small body size.
Zebrafish welfare represents a significant oversight in laboratory animal welfare frameworks. Because they are small, numerous, and technically covered by EU Directive 2010/63 only from the free-feeding larval stage, they often receive less welfare consideration than mammals despite substantial evidence for pain sensitivity and social needs. Suboptimal housing conditions including incorrect temperature, inadequate water quality, and isolation from conspecifics are common in research facilities. Implementing zebrafish-specific welfare standards - including group housing, enrichment, and appropriate water conditions - is both scientifically and ethically important.