Pilot fish usually gather around sharks (also rays and sea turtles). They eat parasites on their host, and small pieces of food that their host does not eat (leftovers). When pilot fish are young, they gather around jellyfish and drifting seaweeds.
Pilot fish follow sharks because other animals which might eat them will not come near a shark. In return, sharks do not eat pilot fish because pilot fish eat their parasites. This is called a "mutualist" relationship. Small pilot fish are often seen swimming into the mouth of a shark to eat small pieces of food from the shark's teeth. Sailors even said that sharks and pilot fish act like close friends. When a ship captured "their" shark, the pilot fish followed the ship. Some people reported that the pilot fish would follow the ship for up to six weeks. And they do show signs of distress in the absence of their shark.
The pilot fish has a dark blue to blackish-silver colour, and are slightly lighter in colour underneath. They have between five and seven dark stripes going from top to bottom. When the fish is excited, these stripes disappear, and three large blue patches appear on its back. The pilot fish is usually about 30 cm long, but sometimes they can be as big as 70cm.
The pilot fish will not hurt people, and they are said to be good to eat. They are difficult to catch, though.
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- Schomburgk, Robert Hermann (1848). History of Barbados: comprising a geographical and statistical description of the island. p. 669. ISBN 0-7146-1948-5.
- Gudger, E. W. (1929). "Some instances of supposed sympathy among fishes". The Scientific Monthly. 28 (3): 267. Bibcode:1929SciMo..28..266G.
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- Randall, John; Allen, Gerald and Steen, Roger (1997). Fishes of the Great Barrier Reef and Coral Sea. University of Hawaii Press. p. 164. ISBN 0824818954.CS1 maint: multiple names: authors list (link)
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- NOAA Library Image: http://www.photolib.noaa.gov/historic/nmfs/figb0368.htm
- Naucrates ductor at FishBase