Angel How Do I Keep Angel Fish From Dying?

How do I keep angel fish from dying? - angel

Hello I am a child of the owner of a pet. In recent times, when the angel fish is replaced in a few days or hours, has died.

Yes, this is the temperature for this type of tropical fish all right, but not the reason. There must be another reason why these Angelfish Secrets. Is there something wrong with my father with the fish?