Zebrafish are used in millions of procedures annually in biomedical research. Their welfare is often underestimated relative to mammals despite evidence of pain processing.
Zebrafish welfare receives less ethical scrutiny than mammalian research subjects despite their enormous numbers. Their pain responses, social needs, and environmental sensitivities are real and measurable. Poorly maintained tank systems cause chronic stress from inadequate oxygen, temperature fluctuation, and social isolation. The scale of zebrafish use means even modest welfare improvements per fish have enormous cumulative impact.