In Ted Hughes's poem "Pike," personification serves to equate the fish with the persona of the poem; thus, with this equality established, the behavior of the person who captures the fish and imprisons them in an aquarium is called into question.
With great poetic skill, Ted Hughes uses personification to position the natural with the human world, juxtaposing the images of the fish with the unnatural world in which man imprisons them for some capricious or cruel intention. For instance, the pike is "stunned by their own grandeur," and the largest pike in the aquarium "spare[s] nobody." This act of natural cruelty leads the persona of the poem to conjure images of a monastery pond in which he once fished that is "as deep as England." Looking into its depths, the persona envisioned "Pike too immense to stir," and he shivered
With the hair frozen on my head
For what might move, for what eye might move.
As one critic remarks, "Fearsome anticipation of what destructive visions form England’s past may visit him seems the focus of ‘Pike’." Thus, the large pike are personified in the persona's mind as ancient soldiers of a medieval Britain, formidable adversaries in their own world and not the artificial one in which he has imposed the young pike. In the natural world, man is not superior to nature; Hughes's use of personification points the reader to this truth.