The maximum size of the John Dory is 2 ft (65 cm) long. The maximum weight is 7 lbs (3 kg).The fish is also called St Pierre or St. Peter.
This is a deep sea fish that has a laterally contracted body. It has a yellow olive color. There are spines on its dorsal fin, and it also has a dark spot on the body. The dark spot is employed by the fish as an “evil eye” if there is an approaching predator.
The fish has a large pair of eyes set on the front of the head. This feature gives it bifocal vision, no matter what the size of the John Dory is. The eyes also have good depth perception, necessary to keep an eye on predators. The eye spot on its side has another useful function. It assists in bewildering fish, making them easy prey.
Origin of the Name
There are many explanations put forward. One suggestion is that the name is derived from John Dory, a figure from a ballad. Some believe that the name John is taken from jaune, French for yellow.
Another account is given by the writer Jules Verne in his book An Antarctic Mystery. In the book, Verne stated the name came from St. Peter, who gave the fish to the Lord upon the Lord’s wishes. A related legend states the dark mark on the fish came from the thumbprint of St. Peter.
The size of the John Dory off New Zealand is the same as other places, but there it is called kuparu by the Maori.
The John Dory has four spines on the anal fin and 10 long spines upon its dorsal fin. The fish has very small sharp scales that are spread all over the body. The body has a round flattened shape, and does not swim very well.
Diet and Predators
The John Dory feeds on numerous types of schooling fish. Among its favorites are sardines and cuttlefish. It also consumes squid. The fish goes after its prey by stalking and then producing a tube from its mouth. This tube is used to get the fish. Its natural enemies are the sharks, particularly the dusk shark.
Distribution, Habitat and Lifespan
The John Dory is found along the coasts of Japan, Europe, Australia, New Zealand and off the coasts of various Southeast Asian countries. The John Dory is also found off the West African coasts. The fish can often be found by the seabed.
Usually they swim 15 ft (5 m) to 1200 ft (360 m) deep. As a rule the fish travels alone. The average John Dory can live for 12 years. They become capable of reproduction around four years of age.
While the size of the John Dory maxes out at two feet, some of the fish do not attain that length. Some of the fish caught are much smaller.