The Ramora is a powerfully magical silver-colored fish from the Indian Ocean, a protected species that in turn is a guardian of seafarers, as the Ramora is capable of anchoring ships. It is protected from poaching by international wizarding law (FB).
May come from the real fish, remora, sometimes called a suckerfish, a family of ray-finned fish . A remora can attach and detach itself to larger marine animals or boats.
Also from remora, the Latin word for delay.
Other than Fantastic Beasts and Where to Find Them, the Ramora does not appear in any of the books.