Marine Life‎ > ‎Indo-Pacific‎ > ‎Fish‎ > ‎

Remoras

Sharksucker

Echeneis naucrates

 
(1: Namara Island, Fiji / 2: Solo Reef, Fiji)

These hitch a ride on larger fish using a suction disk on their forehead.  Other than adding a bit of drag, it doesn't hurt the larger fish.