Fish have incredibly sensitive hearing, much more acute than humans. Their ears are part of this, but the lateral line by which they detect vibrations is largely responsible. When my neighbour across the street shuts their door, the fish in my tank jump. It is said that fish in the aquarium can hear the water running through the pipes in the walls of the house.
As far as the type of music, this is more important than many realize. One reason why fish tanks are not good in rooms with TVs or music systems. Light (from the TV) also plays into this. I've no idea if the fish can hear different "tunes" but they can certainly hear noise and see flashing light and these are stressful.
I remember a National Geographic show on plants' response to music. They were able to prove that the plants were agitated by all rock music, but they were not agitated by quiet classical music. The plants also reacted to the thoughts of a person standing in front of the plant. It was quite remarkable. We still cannot adequately fathom the incredible wonder of life.