Sources : Echeneis
Lucan [1st century CE] (Pharsalia, book 6, verse 797-799): "...the sucking fish / Which holds the vessel back though eastern winds / Make bend the canvas...".
Pliny the Elder [1st century CE] (Natural History, Book 9, 41): There is a quite small fish that frequents rocks, called the sucking-fish. This is believed to make ships go more slowly by sticking to their hulls, from which it has received its name; and for this reason it also has an evil reputation for supplying a love-charm and for acting as a spell to hinder litigation in the courts, which accusations it counterbalances only by its laudable property of stopping fluxes of the womb in pregnant women and holding back the offspring till the time of birth. It is not included however among articles of diet. It is thought by some to have feet, but Aristotle denies this, adding that its limbs resemble wings. - [Rackham translation]
Aelianus [170-230 CE] (On the Characteristics of Animals, Book 1, 36; 2, 17): [Book 1, 36]... the Sucking-fish clings to ships, and from its action we give it its name, Ship-holder. [Book 2, 17] There is a fish whose province is the open sea, black in appearance, as long as an eel of moderate size, and deriving its name from what it does : with evil purpose it meets a vessel running at full speed before the wind, and fastening its teeth into the front of the prow, like a man vigorously curbing with bit and tightened rein an intractable and savage horse, it checks the vessel's onrush and holds it fast. In vain do the sails belly in the middle, to no purpose do the winds blow, and depression comes upon the passengers. But the sailors understand and realize what ails the ship; and it is from this action that the fish has acquired its name, for those who have had experience call it the Ship-holder. - [Scholfield translation]
Isidore of Seville [7th century CE] (Etymologies, Book 12, 6.34): The remora (echenais), a small fish half a foot long, takes its name because it holds a ship fast by clinging to it. Even if winds rush and storms rage, still the ship seems to stand in the sea as if rooted, and is not moved, not as a result of being held back, but simply by being clung to. Latin speakers have named this the mora (delay) because it forces boats to stand still. - [Barney, Lewis, et. al. translation]
Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.33): Echinus is a fish, as Isidore and Jacobus say, a half foot long with such power that it can hold a ship by clinging to it. The winds rush, the storms rage, the waves are lifted, but the ship stands immovable as if rooted, and can neither proceed nor return, the little fish not so much holding it as clinging to it. This indeed seemed incredible to many; but the authors have such faith in this, and such agreement, that no one is ever left to doubt this. In this the blessed Ambrose is the first to agree, the second Jacobus Aconensis, the third Aristotle, the fourth blessed Isidore, the fifth the great Basil. We have therefore set forth the authors of this matter in order of careful narration, because it is truly wonderful and beyond estimation, that a half foot long little fish, not by any violence, but only by clinging, holds back a ship of two hundred feet with its internal weight, so that it cannot be moved even a little. There are fools and stupid people, I do not mean the philosophers, but the impure heretics, who, therefore, find the faith of the Christians unreasonable, because they find its articles to be beyond nature and human power. Tell me, most impudent serpent, what would seem more incredible: either to conceive and give birth to a virgin without a man's seed, or to be able to hold such a mass of a ship motionless against the strongest blasts of the wind by the clinging of a half foot long fish? I believe that reason will dictate to you that the story of the virgin could be believed rather than the that of fish holding back the ship. For horses, porcupines, partridges, and vultures, and many other animals, according to the testimony of blessed Ambrose, without the mixing of seed and without intercourse with males, are certain to conceive only by wind and scent, and to bear offspring, and certainly both are admirable as regards nature and human power. But he excels elegantly in being born to a virgin: for Christ is truly God almighty, who could be born in this way, because he wanted to be born in this way. As for the fish, there is no other reason for the stupendous prodigy, except that God is to be wonderful in his creatures, and the folly of the heretics is thereby confounded, because they do not want to believe anything beyond the common course of nature. [At this point Thomas continues with an account of the sea urchin (text is included there), apparently identifying it with the echeneis.] - [Badke translation/paraphrase]
Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book13.26): and there it is said, yt Enchirius is a fish unneth halfe a foote long, and hath that name of Herendo, cleaving: for though he be full little of body, nevertheles he is most of vertue: for he cleaveth to ye ship & holdeth it still steadfastly in the sea, as though the ship were on grounde therein. Though windes blowe, and waves arise strongly, and woode stormes, that ships may not moove neyther passe. And that Fish holdeth not still the shippe by any craft, but onely by cleaving to ye ship. Latines call this fish Moron. For by strength he maketh the ship to stand, as it is said. Also in Exameron it said of the same Fish, that when he knoweth and feeleth, that tempest of winde and weathers bée great, he commeth & taketh a great stone and holdeth him fast thereby, as it were by an Anker, least he be smitten away, & throwen about with waves of the sea. And so he saveth not himselfe by his own strength, but helpeth to save himselfe by heavinesse and weight, that is not his owne. And is made stedfast and stable against the comming of tempest & storme: and ship men see this, & beware that they be not over set unwarilye with tempest and with stormes, as Ambrose saith, and Beda also. - [Batman]