To divers, the underwater world is silent, and we call the ocean the “silent deep.” But to a fish, the underwater world isn’t silent at all, for fish can “hear” other fish moving through the water and even “hear” the water itself moving.
Fish do not have ears, as animals do, but they do have a structure inside their head that is very much like our own inner ear. This structure is sensitive to vibrations in the water, such as those made by another fish.
Tests have shown that some fish are sensitive to ordinary sounds too. Catfish can probably hear everything we hear!