remora
Concise Oxford English Dictionary © 2008 Oxford University Press:
remora /ˈrɛmərə/
▶noun a slender sea fish which attaches itself to large fish by means of a sucker on top of the head. [Remora remora and other species, family Echeneidae .]
– origin C16: from L., lit. ‘hindrance’ (because of the former belief that the fish slowed down ships).
'remora' also found in these Oxford entries:

