Transcriptomic studies are important tools for understanding the development and function of the different cell types that make up complex tissues. Zebrafish (Danio rerio) is a valuable organism for modeling key aspects of vertebrate development, cell biology, and human disease. However, the small size of individual larvae and relative scarcity of certain cell types in zebrafish can hamper efforts to collect enough pure material for cell type-specific transcriptomic studies. Thus, there is a need in the zebrafish field for spatially and temporally resolved gene expression assays. This chapter will discuss the general principles behind the TU-tagging method to isolate cell type-specific RNAs and provide guidance in designing and executing TU-tagging experiments in zebrafish.