Sound

Through water, sound travels about four times faster than it does through air. So, a fish
can actually "hear" sound through the vibrations that take place in water. By picking up
these vibrations in water, the fish become aware of the feeding frenzies that cause many
fish to conglomerate when the feeding begins. Also, there are fish that are so used to a
routine in their feeding that they start grouping when they hear sounds that normally
precede feeding.