Pilot fish

The pilot fish (Naucrates ductor) is a fish that lives in many places of the world. They live in warm water. They eat parasites on larger fish. 

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.

They are also known to follow ships, sometimes for long distances: many pilot fish have been sighted on the shores of England. 

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.Dixon C.C. 1925. The Sargasso Sea. The Geographical Journal 66 (5): 440. doi:10.2307/1782665. JSTOR 1782665. "They take the hook readily, but go quite insane when hooked, and are difficult to land in spite of their size, 6 to 16 inches".

 Related pages 

 List of fish common names

References

 Further reading 




 NOAA Library Image: http://www.photolib.noaa.gov/historic/nmfs/figb0368.htm

 Other websites 
Naucrates ductor at FishBase

category:Teleosts