Zebrafish have become one of the most important model organisms in biomedical research, yet their welfare needs — as social, active fish requiring specific environmental conditions — are frequently underappreciated.
Zebrafish welfare has improved significantly as their importance in research has grown, but gaps between welfare science and standard practice remain. As social schooling fish, zebrafish experience measurable stress when isolated — yet many experimental protocols require individual housing. Tank enrichment, including plants and visual barriers, reduces aggression and stress. The recognition that zebrafish experience pain has led to improved analgesic protocols in some institutions, though implementation is inconsistent. The Zebrafish Model Organism Database and institutional animal care committees have pushed welfare standards upward, but the sheer volume of zebrafish used (far exceeding any other fish species in research) means aggregate welfare impacts are significant even where per-animal harm is modest.