The fish is never free from anxiety, since big fish are always eager to eat the small fish. All living entities are eaten by bigger living entities. This is the way of material nature.
Nondevotees factually appreciate the wonderful creation of material nature, but they cannot appreciate the intelligence and energy of the Supreme Personality of Godhead, who is behind this material creation.
Sri Chaitanya Caritamrta,
Adi Lila 7.121
The only way to transcend material nature is to do everything for Krishna.
No one has the ability to imitate the activities of material nature as conducted by the Supreme Personality of Godhead.