The zebra danio is the freshwater fish Danio rerio.
Danio rerio is a small cyprinid native to streams, ponds, and rice fields in parts of South Asia, especially India, Bangladesh, Nepal, and Pakistan. Its horizontal blue-and-silver stripes explain the common name zebra danio, while “zebrafish” is the standard name in scientific research.
The species became a major laboratory animal because it breeds readily, develops quickly, and produces transparent embryos. Researchers use it to study development, genetics, regeneration, toxicology, and human disease. Its genome was sequenced in the early 2000s.
Zebra danios are sometimes confused with pearl danios or leopard danios, which are different species or commercially used names. The name Danio rerio identifies the striped species itself, not every small danio sold in aquariums.