Medium-sized (up to 90 cm), elongate and fusiform fishes. Head wide, depressed; a transversely laminated, oval-shaped cephalic disc. Opercle without spines. 8-11 branchiostegal rays. Dorsal fin with 18-45 soft rays. Anal fin with 18-41; dorsal- and anal-fin bases long, lacking spines. Caudal fin slightly forked, emarginate, or slightly rounded in adults; with elongate median caudal fin filament in juveniles of some species. Pectoral fin with 18-32 rays. Pelvic fin with I spine and 5 soft rays. Scales small, cycloid, usually embedded in skin. No swimbladder. Color: body brown, grayish to black, sometimes whitish, with light and dark longitudinal stripes on trunk.|
Similar families occurring in the area. No other family of fishes has a sucking disc dorsally on the head.
Remarks. Attaching to other fishes, cetaceans, sea turtles, whales, or dolphins with a sucking disc on head; a great preference or specificity toward certain hosts in some species. Feeds on parasitic copepods attached to a host and food scraps dropped by the host. No commercial importance, but some species are taken in coastal fisheries along with other fishes and sold in local markets.