Small mineralized structures called scales cover the surfaces of sharks and bony fishes, yet this common term belies an abundant diversity of forms. Shark scales are highly three-dimensional and protrude outwards from the epidermis, ending in swept-back heads that point towards the tail. In contrast, bony fish scales are typically flat embedded plates that overlap considerably with neighboring scales so that just their trailing-edges are free. Here we briefly summarize our work on the morphology of these two surfaces, and we end by discussing future work to examine the hydrodynamic function of shark and bony fish surfaces. Our work uses profilometry and three-dimensional imaging techniques to understand the topography of shark and bony fish surfaces, which provides a quantitative method for comparing surfaces, leading to observations on shared patterns across taxa. For example, shark and bony fish surfaces both exhibit a range of roughness, but shark surfaces tend to have negative skew values, reflecting the relative prominence of valleys and other negative features in their surfaces. In contrast, bony fishes often have positive skew values, indicating the relative prominence of hills and positive surface features. We show how shark scales change in morphology from large feature-less scales on leading-edge surfaces to small highly-overlapping scales on trailing edge surfaces, and we contrast this with bony fishes, that tend to lack scales on their heads but often have only subtle difference in scale morphology down the body. We end by assessing future directions on how the surfaces of sharks and bony fishes behave in flow – in particular we share how mucus may play a role on fish surfaces and how we might begin to link scale morphology and hydrodynamics in sharks.