The remora or suckerfish or (Echeneis naucrates) is a commensal fish that belongs to the family of the Echeneidae. There exist 8 species of Echeneidés, all present in the Western Atlantic zone, out of which 5 are present in the Mediterranean sea. Suckerfishes can attach themselves on the skin of their hosts, in their mouthes or when the host is a fish in its cavities that shelter the gills, thus letting themselves to be carried away. Each species of suckerfish has a host of choice that protects it from possible predators. It is a typical example of commensalism because a suckerfish benefits from its relationship with its host that in turn does not get from it any tangible advantage nor a disadvantage. The very fine and hydrodynamic body of a remora tapering down to its tail does not cause any annoyance to its host.

     A suckerfish (see this link in French) may be attached to the back of its host and so it could find itself upside down ...

     Attached sometimes for long durations to a great choice of hosts (sharks, rays, great bony fishes like groupers for example, turtles, whales, dolphins but also boats), they also follow scubadivers and are known for wanting to attach themselves to their fins or legs. Sometimes found around specific reefs, juvenile remoras behave like cleaner fishes. You have an example of such cleaning activity on a goliath grouper [see below the video entitled "Rémora or/ou Suckerfish(3)"].

     During the fishing season, some fishermen used them : the line is attached to the caudal fin of a suckerfish and the fish is then released so that it can attach itself to another fish, and therefore the remora and its host are hauled back to the fishing boat.