Yes, fish have ears and can hear.  But most fish hear very poorly.  You cannot see a fish’s ears because they are buried deep inside its head.  In addition, many kinds of fish also have tiny sense organs arranged in lines along the sides of their bodies which are called the lateral lines.

This organ feels vibrations in the water.  It lets the fish know what’s going on around it, even if it does not see or hear anything.  Through its lateral line organ, a fish can sense the vibrations of your footsteps along the banks of a stream and swim away. –Dick Rogers