This study on the zebrafish optic tectum is a series of four images with magnifications ranging from the SEM block face overview to of the zebrafish head to high magnification (80,000X) showing optic tectum synapse. This first image is a bloc face SEM image at 200x of the epon embedded zebrafish head. The second image is another block face SEM low magnification image of the tectum. The third image is a 60,000X TEM image of a OTO fixation and copper lead en bloc staining of zebrafish optic tectum synapse. The fourth image is a 80,000X TEM image of a zebrafish optic tectum synapse. This image larval zebrafish image was collected on a Gatan 3View® serial block face scanning electron microscope (SBFSEM). The 3View® is attached to a FEI Quanta 600 FEG SEM. Block face imaging is a way to look at epon embedded specimens using backscattered electrons in the SEM. A diamond knife in the vacuum chamber of the SEM cuts hundreds of ultrathin serial sections, thus gathering a perfected registered stack of images. Reference for SBFSEM: Denk, W. and H. Horstmann. Serial block face scanning electron microscopy to reconstruct three- dimensional tissue nanostructure. PloS Biology vol 2, 11; e329 doi:10.1371/journal.pbio.0020329 Microwave processing, osmium tetroxoxide/osmid procedure for enhancing membranes, and copper lead en bloc staining. Procedure for specimen preparation available at http://www.stanford.edu/~redhair/JoAnn_Buchanan.