Clingfishes (Gobiesocidae) are a diverse group of small, nearshore marine fishes. They are equipped with a ventral suctorial disc made up of elements from the pectoral and pelvic girdles. Found in a wide range of microhabitats, clingfishes use their disc to adhere to rocks, shells, macroalgae, seagrass, crinoids, and other substrates. Clingfishes have extensive morphological variation in their adhesive discs and their cranial features, that might be tied to their ecology. We use a recently published clingfish phylogeny and micro-CT based 3D geometric morphometrics to quantify morphological diversity in 72 of 181 species of clingfishes. We placed fixed and semi-landmarks on clingfish skulls and the bony elements of the adhesive disc using SlicerMorph. A remarkable aspect of clingfish diversity are the repeated transitions to living on the blades of macroalgae and seagrasses all over the world. Macroalgae/seagrass specialists have converged on similar cranial and suctorial morphologies (e.g., narrower and more elongate skulls, and narrower and taller pelvic girdles) than the rock dwelling species that are their nearest relations. Other extreme habitat specialists: two obligate crinoid species, and a single interstitial species, occupy their own regions of the morphospace.