Handling by humans damages this mucus, leaving the fish vulnerable to disease when returned to the water. Most fish have a row of tiny pores on their sides called the lateral line. These act as a hearing aid, making them very sensitive to vibrations and reflections. Outside the water, however, they can hear no sounds. They also have a swim bladder to help them balance and move from deep to shallow water.
Fish are short sighted.
Their eyes can look in separate directions at the same time. They do have colour vision, though. Hence the use by anglers of brightly coloured bait. Just as we use our hands, fish use their tongues and lips to build nests, gather food and hide their young from danger. Fish meat has no complex carbohydrates and no fibre.