Fish have an inner ear with sensory chambers lined with sensory hair cells. Each ear chamber also contains an ear stone called an otolith. Fish can hear through the vibrations in their inner ear.  The Australian Museum describes the physical process:  “When sound vibrations pass through a fish, the differences in vibrations between the dense otoliths and the sensory hair cells is detected by the auditory nerves. In some fishes the gas bladder (sometimes called the swim bladder) aids in hearing by transmitting vibrations to the inner ear.” So, yes, fish can hear you say their names, but that doesn’t mean they understand you. Sound doesn’t travel well between air and water, so your voice sounds like a muffled garble to a fish.