In our laboratory, we study thrombopoiesis and hemostasis using zebrafish as a model organism to unravel the mechanisms of differentiation and development of thrombocytes. We have shown in our earlier work that thrombocytes are functional equivalents of platelets and have transcriptional machinery similar to megakaryocytes. We recently found evidence that hox genes play a role in their development. We used piggyback gene knockdown and thrombocyte quantification assays to understand the influence of these ancient developmental regulators on thrombopoiesis. In this chapter, we describe methods used to discover these hox genes.