Echeneis naucrates can be easily spotted due to the sucking disc on top of its head. Its sucking organ consists of numerous pairs of crests, which originated from a highly modified spiny dorsal fin. This sucking disc is capable of producing a strong vacuum that the species uses to attach to their hosts. The fish is usually 11 or 12 times as long as it is wide, and about five and a half times the length of its head. The slim body usually has a dark stripe on the side with narrower pale edges (Field 1998). The sharksucker's tail is pointed, and the jaw is protruded. Echeneis naucrates' pectoral and ventral fins are dark in color, and the belly is a dark brownish color. The dorsal and anal fins are black, and are outlined with a lighter shade. Sharksuckers can reach approximately 100 centimeters in length, yet smaller ones are found more frequently. Adult females and males are difficult to distinguish. After the formation of the sucking disc, the young start to resemble the adults (Bigelow 1953).

Average mass: 2.01 g.