Marianne Moore wrote "The Fish" in 1918 but it was published later in her first collection, Poems, in 1921. This collection was published, without her knowledge, in England by two of Moore's friends. An example of rhymed syllabic verse, "The Fish" highlights Moore's ability for precise visual description. Ironically, the poem is not about fish at all, but rather the relationship among a seaside cliff, sea life, and the sea itself. Sunlight acts upon the sea and its creatures, and the sea acts upon a cliff. Moore highlights the interdependence of these elements in the shape of the poem, which moves like a wave, surging towards a subject, then retreating from it. The narrator of the poem describes this interdependence in a hard, emotionally detached manner. Her images paradoxically suggest both fecundity and abundance and starkness and death. This dichotomy drives the poem, but Moore never resolves the paradox; rather, she suggests that it is a necessary part of the world. The processes of life and death are evident everywhere, and as much a part of the human as the natural landscape.

Moore was inspired by the natural world. She frequently wrote about animals, domestic and exotic, often preferring the non-human world over the human world. Moore was also interested in modern painting and studied color theory, which some critics mention as influencing "The Fish." Other possible influences were her brother Warner's passion for sailing and Moore's deep respect for him. When the poem was republished in her second collection, Observations (1924), Moore used six-line stanzas instead of five. However, it is the five-line version that has been widely anthologized and written about.