In this work we demonstrate large-scale high-sensitivity optical diffraction tomography (ODT) of zebrafish. We make this possible by three improvements. First, we obtain a large field of view while still maintaining a high resolution by using a high magnification over numerical aperture ratio digital holography set-up. With the inclusion of phase shifting we operate close to the optimum magnification over numerical aperture ratio. Second, we decrease the noise in the reconstructed images by implementing off-axis sample placement and numerical focus tracking in combination with the acquisition of a large number of projections. Although both techniques lead to an increase in sensitivity independently, we show that combining them is necessary in order to make optimal use of the potential gain offered by each respective method and obtain a refractive index (RI) sensitivity of 8⋅10 −5 . Third, we optimize the optical clearing procedure to prevent scattering and refraction to occur. We demonstrate our technique by imaging a zebrafish larva over 13 mm 3 field of view with 4 micrometer resolution. Finally, we demonstrate a clinical application of our technique by imaging an entire adult cryoinjured zebrafish heart.