All fishes are adapted to live in water because they dont have
lungs they have gills which means that lungs work with air and
gills work with water. Have you ever thought does a fish dies when
taken out of the water it is because gills are the only way a fish
breathes through. Gills work when a current of water slide over
them so when the fish is taken out of the water, the gills stop
working because the current of water didnt slid over it.
They have wide eyes to see predators swimming around them.