Question

Why does fish die when kept outside water even though there is oxygen the surrounding air?

Answer 1

a fish die when kept outside the water even though the oxygen is present because fishes PR we can say aquatic animals mostly take dissolved oxygen from water by the help of gills and in fishes gills are present which are only able to take dissolved oxygen fishes lavk lungs so they can't take oxygen from air

Answer 2

Fish extract oxygen from water using gills, but gills cannot extract oxygen from air.  

A few species of fish (e.g. lungfish, snakehead) have some ability to extract oxygen from air (e.g. lungfish use a modified swim bladder like a lung) and can survive short trips across dry land from one shallow pool to another.