Note: The following is taken in part from my memoir, Sailing with Impunity: Adventure in the South Pacific.
On the first day out of Bora Bora, when checking the jib and looking over the bow, Bruce noticed we had a little tagalong, a pilot fish. A beautiful little fish, silver with dark vertical stripes, the pilot fish was about 12 inches long. Impunity was scooting right along at 7 knots and the little fellow had no trouble keeping up.
Pilot fish normally congregate around sharks, rays, and sea turtles. Sharks, particularly the oceanic whitetip, are the pilot fish’s most common and advantageous companion. The ocean can be a perilous place for small fish with hungry predators lurking to strike the most vulnerable. For protection, many small fish travel in large schools, but the pilot fish has made a reciprocal partnership by offering a unique service: keeping the sharks free of harmful parasites and cleaning up bits of excess food. The pilot fish apparently knows that when it comes to making powerful friends, nothing beats the shark and the assurance of safe passage.
There is such trust between them that pilot fish are even known to enter their sharks’ mouths to nibble away food debris. It is extremely rare that a shark will eat a pilot fish—there seems to be a working bond between them.
Pilot fish are also known to swim along with boats and ships. Our little tagalong was probably feeding off Impunity’s “jaw” or hull. We enjoyed his company for four days.