What is the tone of the poem "Woman Before the Aquarium"?

In the opening stanza of the poem, the speaker watches a goldfish in a fishbowl and makes a metaphor of a gold watch. She collects the natural objects in the bowl: “water,” “rivulets,” “rocks,” “shells,” and arranges them into a painting. She is quiet, watchful, and reflective. This meditation takes her into a transformative state and she enters into the painting gently, “slowly,” by way of another natural object, a pinecone. A memory is released of a sexual encounter, perhaps a rape, and the word “fear” is used, but the speaker remains her meditative state. She is protected within the painting; her desire to be a “mermaid,” an “odalisque,” renders her “untouchable.” Although the fear is present, she is not afraid; rather she has “power.” Even the “face” and “haircut” she is “dressed” in are protections for her as the “plain desk of ordinary work” allow her to not know the fear.  The speaker sees the aquarium as a “lantern” and a “light,” something mysterious from the “underworld.” She easily places herself this “shore” as a shining “messenger” to “kindred.” The tone of the poem is ironic because even as women may be “crush[ed]” by memory of sexual subjugation and racial fear, the speaker creates a green and gold “souvenir” that acts as a beautiful message of hope, of “swimming” free. Rather than being imprisoned by the fishbowl, by beauty and femininity, the woman shows how to be powerfully unrestrained.