The model organism Danio rerio, also known as the zebrafish, is an excellent system for studying the developmental process of hematopoiesis. It is an ideal model for in vivo imaging, and it is useful for large-scale genetic screens. These have led to the discovery of previously unknown players in hematopoiesis, as well as helped our understanding of hematopoietic development. In this review, we will summarize hematopoiesis in the zebrafish and discuss how genetic approaches using the zebrafish system have helped to build our current knowledge in the field of hematopoiesis.