"Pike" is a poem comprised of eleven stanzas of four lines each. There is no rhyme scheme. The poem's subject is the pike (a type of fish): the speaker describes pike in general and moves on to discuss his own particular experiences with pike and how they have made him feel.

At the beginning of the poem, he discusses small pike, "three inches long," and notes that they seem to be "killers" from the moment they emerge from the egg. In the poet's view, these tiny creatures imagine themselves to be "a hundred feet" in length and in complete control of their surroundings, so conscious are they of their own "grandeur." The speaker emphasizes the violent nature of the fish, describing them as "malevolent." While the fish are not personified as such—if anything, they are painted as a "darkness" far beyond human understanding—they certainly appear as having their own motivations, from their evil "grin" to their watchful gaze.

The poet describes having once fished three pike and kept them in a tank. These fish were fed on fry, but the experiment was a failure—in the end, only one fish was left, retaining its malevolent grin in the face of the fact that the other two fish had killed each other. The "iron" in the eye of the dead fish seemed to dissipate only then, in death.

The final section of the poem describes how the poet had fished in an enormous pond, conscious of its extreme depth: "as deep as England." In this pond were "immense" pike, which felt so "old" and powerful to the speaker that he did not dare to fish at night, afraid of what "eye" might alight upon him from beneath the surface of the dark pond. The speaker creates a vivid sense of his own fear, the "hair frozen" on his head and the gentle sounds of owls in the nearby woods. As he fishes, the speaker is aware of the "darkness" of the pike moving toward him, "watching." There is a strong sense that the pike are, in the end, ageless things, more powerful than the lone human could ever be.