Apart

from the irritation caused by lice and what are nicknamed
fleas, fish are met with in a state so motionless that one might
easily catch them by hand; and, as a matter of fact, these little
creatures, if the fish remain long in one position, will attack them
in myriads and devour them. For these parasites are found in the
depths of the sea, and are so numerous that they devour any bait
made of fish's flesh if it be left long on the ground at the bottom;
and fishermen often draw up a cluster of them, all clinging on to
the bait.