Zebrafish are among the fastest-growing laboratory animal species. Their welfare needs are often underappreciated because they are fish, but evidence supports that they require specific care.
The rapid growth of zebrafish use in research has not been matched by equivalent development of zebrafish-specific welfare standards and refinements. Many facilities apply basic care standards without the species-specific guidance available for rodents. Zebrafish are social animals whose welfare is improved by group housing and visual access to conspecifics. Their small size and short lifespan have contributed to an assumption of lower sentience that is not supported by neurobiological evidence. Water quality represents the most critical welfare variable, with suboptimal pH, temperature, oxygen, or ammonia levels causing chronic suffering that is easy to prevent with appropriate monitoring. Developing and implementing zebrafish-specific welfare refinements is a priority as their use in research continues to grow.