Nanoscale imaging of all anatomical structures over whole vertebrates is needed for a systematic understanding of human diseases, but this has not yet been achieved. Here, we demonstrate whole-ExM, which enables nanoscale imaging of all anatomical structures of whole zebrafish larvae by labeling the proteins of the larvae with fluorophores and expanding them four-fold. We first optimize the fluorophore selection and labeling procedure to visualize a broader range of anatomical structures. We then develop an expansion protocol for zebrafish larvae having calcified body parts. Through this process, we visualize the nanoscale details of diverse larvae organs, which have corresponding organ counterparts in humans, over the intact larvae. We show that whole-ExM retains the fluorescence signals of fluorescent proteins, and its resolution is high enough to visualize various structures that can be imaged only with electron microscopy. Whole-ExM would enable the nanoscale study of the molecular mechanisms of human diseases.