Zebrafish are increasingly used in biomedical research. Their welfare needs in laboratory settings, particularly regarding social housing and environmental enrichment, deserve more attention than they typically receive.
Zebrafish occupy an interesting position in laboratory animal welfare because their use has grown enormously partly due to the perception that they require less stringent welfare protection than mammals. This perception is increasingly challenged by evidence that zebrafish experience stress, have analgesic responses to painful stimuli, and show behavioral indicators of poor welfare in understimulating environments. The social nature of zebrafish means isolated housing - common in individual tank systems - causes measurable psychological stress. Applying the three Rs framework rigorously to zebrafish research would improve their welfare substantially, including social housing, environmental enrichment, and careful consideration of procedures that cause pain or distress.