Zebrafish in hematology: sushi or science?

After a decade of the modern era of zebrafish hematology research, what have been their major contributions to hematology and what challenges does the model face? This review argues that, in hematology, zebrafish have demonstrated their suitability, are proving their utility, have supplied timely and novel discoveries, and are poised for further significant contributions. It presents an overview of the anatomy, physiology, and genetics of zebrafish hematopoiesis underpinning their use in hematology research. Whereas reverse genetic techniques enable func-tional studies of particular genes of interest, forward genetics remains zebrafish's particular strength. Mutants with diverse and interesting hematopoietic defects are emerging from multiple genetic screens. Some mutants model hereditary blood diseases, occasionally leading to disease genes first; others provide insights into developmental hematology. Models of malignant hematologic disorders provide tools for drug-target and pharmaceutics discovery. Numerous transgenic zebrafish with fluorescently marked blood cells enable live-cell imaging of inflammatory re-sponses and host-pathogen interactions previously inaccessible to direct observation in vivo, revealing unexpected aspects of leukocyte behavior. Zebrafish disease models almost uniquely provide a basis for efficient whole animal chemical library screens for new therapeutics. Despite some limitations and challenges, their successes and discovery potential mean that zebrafish are here to stay in hematology research.