Although Marcellus’s captivity in the aquarium is a central device within the novel, each of the central characters struggles with captivity in their own way. At the opening of the novel, Marcellus informs the reader that he “was brought here as a juvenile. I shall die here, in this tank” (2). He has given himself over to the idea that he will never see his home again and uses the time he has left to help his new friends. By the end of the novel, he is surprised to be returned to the open sea and to the freedom he believed was out of reach forever. His personal story moves from the objective value of captivity to the objective value of freedom.

Tova also cycles through these values in her own way. At the beginning of the novel, she is as free as it is possible for an elderly woman to be; she is financially secure, in good health, and has no dependents for which she is responsible. This puts her in direct juxtaposition to Marcellus, who lives in a literal cage. Early on her freedom is also juxtaposed against the final years of her brother, who lived out his life in a closed and restricted retirement home.