Κώλυμα. The remoras (/ˈrɛmərəs/), sometimes called suckerfish, are a family (Echeneidae) of ray-finned fish in the order Perciformes. [1][2] They grow to 30–90 cm (0. 98–2. 95 ft) long, and their distinctive first dorsal fins take the form of a modified oval, sucker-like organ with slat-like structures that open and close to create suction and take a firm hold against the skin of larger marine animals.